use bios directly in the log code v4

use bios directly in the log code v4

[Christoph Hellwig]

Hi all,

this series switches the log writing and log recovery code to use bios
directly, and remove various special cases from the buffer cache code.

A git tree is available here:

    git://git.infradead.org/users/hch/xfs.git xfs-log-bio

Gitweb:

    http://git.infradead.org/users/hch/xfs.git/shortlog/refs/heads/xfs-log-bio

Chances since v3:
 - add a few additional cleanup patches
 - clean up iclog allocation
 - drop a not required vmap invalidation
 - better document the iclog size fields
 - fix vmap invalidation

Changes since v2:
 - rename the 'flush' flag to 'need_flush'
 - spelling fixes
 - minor cleanups

Changes since v1:
 - rebased to not required the log item series first
 - split the bio-related code out of xfs_log_recover.c into a new file
   to ease using xfs_log_recover.c in xfsprogs
 - use kmem_alloc_large instead of vmalloc to allocate the buffer
 - additional minor cleanups

[PATCH 01/24] xfs: remove the no-op spinlock_destroy stub

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_linux.h | 2 --
 fs/xfs/xfs_log.c   | 2 --
 2 files changed, 4 deletions(-)

diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index edbd5a210df2..b78287666309 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -110,8 +110,6 @@ typedef __u32			xfs_nlink_t;
 #define current_restore_flags_nested(sp, f)	\
 		(current->flags = ((current->flags & ~(f)) | (*(sp) & (f))))
 
-#define spinlock_destroy(lock)
-
 #define NBBY		8		/* number of bits per byte */
 
 /*
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 457ced3ee3e1..a2048e46be4e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1580,7 +1580,6 @@ xlog_alloc_log(
 			xfs_buf_free(iclog->ic_bp);
 		kmem_free(iclog);
 	}
-	spinlock_destroy(&log->l_icloglock);
 	xfs_buf_free(log->l_xbuf);
 out_free_log:
 	kmem_free(log);
@@ -2027,7 +2026,6 @@ xlog_dealloc_log(
 		kmem_free(iclog);
 		iclog = next_iclog;
 	}
-	spinlock_destroy(&log->l_icloglock);
 
 	log->l_mp->m_log = NULL;
 	kmem_free(log);
-- 
2.20.1

[PATCH 02/24] xfs: remove the never used _XBF_COMPOUND flag

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index d0b96e071cec..4f2c2bc43003 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -49,7 +49,6 @@ typedef enum {
 #define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
 #define _XBF_KMEM	 (1 << 21)/* backed by heap memory */
 #define _XBF_DELWRI_Q	 (1 << 22)/* buffer on a delwri queue */
-#define _XBF_COMPOUND	 (1 << 23)/* compound buffer */
 
 typedef unsigned int xfs_buf_flags_t;
 
@@ -69,8 +68,7 @@ typedef unsigned int xfs_buf_flags_t;
 	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
 	{ _XBF_PAGES,		"PAGES" }, \
 	{ _XBF_KMEM,		"KMEM" }, \
-	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
-	{ _XBF_COMPOUND,	"COMPOUND" }
+	{ _XBF_DELWRI_Q,	"DELWRI_Q" }
 
 
 /*
-- 
2.20.1

[PATCH 03/24] xfs: renumber XBF_WRITE_FAIL

[Christoph Hellwig]

Assining a numerical value that is not close to the flags
defined near by is just asking for conflicts later on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4f2c2bc43003..15f6ce3974ac 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -34,7 +34,7 @@ typedef enum {
 #define XBF_ASYNC	 (1 << 4) /* initiator will not wait for completion */
 #define XBF_DONE	 (1 << 5) /* all pages in the buffer uptodate */
 #define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
-#define XBF_WRITE_FAIL	 (1 << 24)/* async writes have failed on this buffer */
+#define XBF_WRITE_FAIL	 (1 << 7) /* async writes have failed on this buffer */
 
 /* I/O hints for the BIO layer */
 #define XBF_SYNCIO	 (1 << 10)/* treat this buffer as synchronous I/O */
-- 
2.20.1

[PATCH 04/24] xfs: make mem_to_page available outside of xfs_buf.c

[Christoph Hellwig]

Rename the function to kmem_to_page and move it to kmem.h together
with our kmem_large allocator that may either return kmalloced or
vmalloc pages.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/kmem.h    |  8 ++++++++
 fs/xfs/xfs_buf.c | 13 +------------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
index 8e6b3ba81c03..267655acd426 100644
--- a/fs/xfs/kmem.h
+++ b/fs/xfs/kmem.h
@@ -124,4 +124,12 @@ kmem_zone_zalloc(kmem_zone_t *zone, xfs_km_flags_t flags)
 	return kmem_zone_alloc(zone, flags | KM_ZERO);
 }
 
+static inline struct page *
+kmem_to_page(void *addr)
+{
+	if (is_vmalloc_addr(addr))
+		return vmalloc_to_page(addr);
+	return virt_to_page(addr);
+}
+
 #endif /* __XFS_SUPPORT_KMEM_H__ */
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 548344e25128..ade6ec28e1c9 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -933,17 +933,6 @@ xfs_buf_set_empty(
 	bp->b_maps[0].bm_len = bp->b_length;
 }
 
-static inline struct page *
-mem_to_page(
-	void			*addr)
-{
-	if ((!is_vmalloc_addr(addr))) {
-		return virt_to_page(addr);
-	} else {
-		return vmalloc_to_page(addr);
-	}
-}
-
 int
 xfs_buf_associate_memory(
 	xfs_buf_t		*bp,
@@ -976,7 +965,7 @@ xfs_buf_associate_memory(
 	bp->b_offset = offset;
 
 	for (i = 0; i < bp->b_page_count; i++) {
-		bp->b_pages[i] = mem_to_page((void *)pageaddr);
+		bp->b_pages[i] = kmem_to_page((void *)pageaddr);
 		pageaddr += PAGE_SIZE;
 	}
 
-- 
2.20.1

[PATCH 05/24] xfs: remove the l_iclog_size_log field from strut xlog

[Christoph Hellwig]

This field is never used, so we can simply kill it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c      | 9 ---------
 fs/xfs/xfs_log_priv.h | 1 -
 2 files changed, 10 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index a2048e46be4e..8033b64092bb 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1307,7 +1307,6 @@ xlog_get_iclog_buffer_size(
 	struct xfs_mount	*mp,
 	struct xlog		*log)
 {
-	int size;
 	int xhdrs;
 
 	if (mp->m_logbufs <= 0)
@@ -1319,13 +1318,6 @@ xlog_get_iclog_buffer_size(
 	 * Buffer size passed in from mount system call.
 	 */
 	if (mp->m_logbsize > 0) {
-		size = log->l_iclog_size = mp->m_logbsize;
-		log->l_iclog_size_log = 0;
-		while (size != 1) {
-			log->l_iclog_size_log++;
-			size >>= 1;
-		}
-
 		if (xfs_sb_version_haslogv2(&mp->m_sb)) {
 			/* # headers = size / 32k
 			 * one header holds cycles from 32k of data
@@ -1346,7 +1338,6 @@ xlog_get_iclog_buffer_size(
 
 	/* All machines use 32kB buffers by default. */
 	log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
-	log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
 
 	/* the default log size is 16k or 32k which is one header sector */
 	log->l_iclog_hsize = BBSIZE;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index b5f82cb36202..78a2abeba895 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -361,7 +361,6 @@ struct xlog {
 	int			l_iclog_heads;  /* # of iclog header sectors */
 	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
 	int			l_iclog_size;	/* size of log in bytes */
-	int			l_iclog_size_log; /* log power size of log */
 	int			l_iclog_bufs;	/* number of iclog buffers */
 	xfs_daddr_t		l_logBBstart;   /* start block of log */
 	int			l_logsize;      /* size of log in bytes */
-- 
2.20.1

Re: [PATCH 05/24] xfs: remove the l_iclog_size_log field from strut xlog

[Dave Chinner]

On Wed, Jun 05, 2019 at 09:14:52PM +0200, Christoph Hellwig wrote:
> This field is never used, so we can simply kill it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I do find it amazing how many of these "unused things" we are still
removing after all this time....

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH 05/24] xfs: remove the l_iclog_size_log field from strut xlog

[Darrick J. Wong]

On Wed, Jun 05, 2019 at 09:14:52PM +0200, Christoph Hellwig wrote:
> This field is never used, so we can simply kill it.

s/strut xlog/struct xlog/ in the subject; will fix it in the series if I
end up pulling it in...

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D


> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_log.c      | 9 ---------
>  fs/xfs/xfs_log_priv.h | 1 -
>  2 files changed, 10 deletions(-)
> 
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index a2048e46be4e..8033b64092bb 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1307,7 +1307,6 @@ xlog_get_iclog_buffer_size(
>  	struct xfs_mount	*mp,
>  	struct xlog		*log)
>  {
> -	int size;
>  	int xhdrs;
>  
>  	if (mp->m_logbufs <= 0)
> @@ -1319,13 +1318,6 @@ xlog_get_iclog_buffer_size(
>  	 * Buffer size passed in from mount system call.
>  	 */
>  	if (mp->m_logbsize > 0) {
> -		size = log->l_iclog_size = mp->m_logbsize;
> -		log->l_iclog_size_log = 0;
> -		while (size != 1) {
> -			log->l_iclog_size_log++;
> -			size >>= 1;
> -		}
> -
>  		if (xfs_sb_version_haslogv2(&mp->m_sb)) {
>  			/* # headers = size / 32k
>  			 * one header holds cycles from 32k of data
> @@ -1346,7 +1338,6 @@ xlog_get_iclog_buffer_size(
>  
>  	/* All machines use 32kB buffers by default. */
>  	log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
> -	log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
>  
>  	/* the default log size is 16k or 32k which is one header sector */
>  	log->l_iclog_hsize = BBSIZE;
> diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
> index b5f82cb36202..78a2abeba895 100644
> --- a/fs/xfs/xfs_log_priv.h
> +++ b/fs/xfs/xfs_log_priv.h
> @@ -361,7 +361,6 @@ struct xlog {
>  	int			l_iclog_heads;  /* # of iclog header sectors */
>  	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
>  	int			l_iclog_size;	/* size of log in bytes */
> -	int			l_iclog_size_log; /* log power size of log */
>  	int			l_iclog_bufs;	/* number of iclog buffers */
>  	xfs_daddr_t		l_logBBstart;   /* start block of log */
>  	int			l_logsize;      /* size of log in bytes */
> -- 
> 2.20.1
> 

[PATCH 06/24] xfs: cleanup xlog_get_iclog_buffer_size

[Christoph Hellwig]

We don't really need all the messy branches in the function, as it
really does three things, out of which 2 are common for all branches:

 1) set up mount point log buffer size and count values if not already
    done from mount options
 2) calculate the number of log headers
 3) set up all the values in struct xlog based on the above

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c | 52 ++++++++++--------------------------------------
 1 file changed, 11 insertions(+), 41 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 8033b64092bb..3e7b046e04b5 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1301,56 +1301,26 @@ xlog_iodone(xfs_buf_t *bp)
  * If the filesystem blocksize is too large, we may need to choose a
  * larger size since the directory code currently logs entire blocks.
  */
-
 STATIC void
 xlog_get_iclog_buffer_size(
 	struct xfs_mount	*mp,
 	struct xlog		*log)
 {
-	int xhdrs;
-
 	if (mp->m_logbufs <= 0)
-		log->l_iclog_bufs = XLOG_MAX_ICLOGS;
-	else
-		log->l_iclog_bufs = mp->m_logbufs;
+		mp->m_logbufs = XLOG_MAX_ICLOGS;
+	if (mp->m_logbsize <= 0)
+		mp->m_logbsize = XLOG_BIG_RECORD_BSIZE;
+
+	log->l_iclog_bufs = mp->m_logbufs;
+	log->l_iclog_size = mp->m_logbsize;
 
 	/*
-	 * Buffer size passed in from mount system call.
+	 * # headers = size / 32k - one header holds cycles from 32k of data.
 	 */
-	if (mp->m_logbsize > 0) {
-		if (xfs_sb_version_haslogv2(&mp->m_sb)) {
-			/* # headers = size / 32k
-			 * one header holds cycles from 32k of data
-			 */
-
-			xhdrs = mp->m_logbsize / XLOG_HEADER_CYCLE_SIZE;
-			if (mp->m_logbsize % XLOG_HEADER_CYCLE_SIZE)
-				xhdrs++;
-			log->l_iclog_hsize = xhdrs << BBSHIFT;
-			log->l_iclog_heads = xhdrs;
-		} else {
-			ASSERT(mp->m_logbsize <= XLOG_BIG_RECORD_BSIZE);
-			log->l_iclog_hsize = BBSIZE;
-			log->l_iclog_heads = 1;
-		}
-		goto done;
-	}
-
-	/* All machines use 32kB buffers by default. */
-	log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
-
-	/* the default log size is 16k or 32k which is one header sector */
-	log->l_iclog_hsize = BBSIZE;
-	log->l_iclog_heads = 1;
-
-done:
-	/* are we being asked to make the sizes selected above visible? */
-	if (mp->m_logbufs == 0)
-		mp->m_logbufs = log->l_iclog_bufs;
-	if (mp->m_logbsize == 0)
-		mp->m_logbsize = log->l_iclog_size;
-}	/* xlog_get_iclog_buffer_size */
-
+	log->l_iclog_heads =
+		DIV_ROUND_UP(mp->m_logbsize, XLOG_HEADER_CYCLE_SIZE);
+	log->l_iclog_hsize = log->l_iclog_heads << BBSHIFT;
+}
 
 void
 xfs_log_work_queue(
-- 
2.20.1

Re: [PATCH 06/24] xfs: cleanup xlog_get_iclog_buffer_size

[Dave Chinner]

On Wed, Jun 05, 2019 at 09:14:53PM +0200, Christoph Hellwig wrote:
> We don't really need all the messy branches in the function, as it
> really does three things, out of which 2 are common for all branches:
> 
>  1) set up mount point log buffer size and count values if not already
>     done from mount options
>  2) calculate the number of log headers
>  3) set up all the values in struct xlog based on the above
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Nice cleanup!

Reviewed-by: Dave Chinner <dchinner@redhat.com>

-- 
Dave Chinner
david@fromorbit.com

[PATCH 07/24] xfs: reformat xlog_get_lowest_lsn

[Christoph Hellwig]

Reformat xlog_get_lowest_lsn to our usual style.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 3e7b046e04b5..eececb847f8d 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2632,27 +2632,23 @@ xlog_state_clean_log(
 
 STATIC xfs_lsn_t
 xlog_get_lowest_lsn(
-	struct xlog	*log)
+	struct xlog		*log)
 {
-	xlog_in_core_t  *lsn_log;
-	xfs_lsn_t	lowest_lsn, lsn;
+	struct xlog_in_core	*iclog = log->l_iclog;
+	xfs_lsn_t		lowest_lsn = 0, lsn;
 
-	lsn_log = log->l_iclog;
-	lowest_lsn = 0;
 	do {
-	    if (!(lsn_log->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_DIRTY))) {
-		lsn = be64_to_cpu(lsn_log->ic_header.h_lsn);
-		if ((lsn && !lowest_lsn) ||
-		    (XFS_LSN_CMP(lsn, lowest_lsn) < 0)) {
+		if (iclog->ic_state & (XLOG_STATE_ACTIVE | XLOG_STATE_DIRTY))
+			continue;
+
+		lsn = be64_to_cpu(iclog->ic_header.h_lsn);
+		if ((lsn && !lowest_lsn) || XFS_LSN_CMP(lsn, lowest_lsn) < 0)
 			lowest_lsn = lsn;
-		}
-	    }
-	    lsn_log = lsn_log->ic_next;
-	} while (lsn_log != log->l_iclog);
+	} while ((iclog = iclog->ic_next) != log->l_iclog);
+
 	return lowest_lsn;
 }
 
-
 STATIC void
 xlog_state_do_callback(
 	struct xlog		*log,
-- 
2.20.1

[PATCH 08/24] xfs: remove XLOG_STATE_IOABORT

[Christoph Hellwig]

This value is the only flag in ic_state, which we otherwise use as
a state.  Switch it to a new debug-only field and also report and
actual error in the buffer in the I/O completion path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c      | 20 +++++++++++---------
 fs/xfs/xfs_log_priv.h |  4 +++-
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index eececb847f8d..1af9302fbe1e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1257,16 +1257,16 @@ xlog_iodone(xfs_buf_t *bp)
 	struct xlog		*l = iclog->ic_log;
 	int			aborted = 0;
 
+#ifdef DEBUG
+	/* treat writes with injected CRC errors as failed */
+	if (iclog->ic_fail_crc)
+		bp->b_error = -EIO;
+#endif
+
 	/*
-	 * Race to shutdown the filesystem if we see an error or the iclog is in
-	 * IOABORT state. The IOABORT state is only set in DEBUG mode to inject
-	 * CRC errors into log recovery.
+	 * Race to shutdown the filesystem if we see an error.
 	 */
-	if (XFS_TEST_ERROR(bp->b_error, l->l_mp, XFS_ERRTAG_IODONE_IOERR) ||
-	    iclog->ic_state & XLOG_STATE_IOABORT) {
-		if (iclog->ic_state & XLOG_STATE_IOABORT)
-			iclog->ic_state &= ~XLOG_STATE_IOABORT;
-
+	if (XFS_TEST_ERROR(bp->b_error, l->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
 		xfs_buf_ioerror_alert(bp, __func__);
 		xfs_buf_stale(bp);
 		xfs_force_shutdown(l->l_mp, SHUTDOWN_LOG_IO_ERROR);
@@ -1881,13 +1881,15 @@ xlog_sync(
 	 * write on I/O completion and shutdown the fs. The subsequent mount
 	 * detects the bad CRC and attempts to recover.
 	 */
+#ifdef DEBUG
 	if (XFS_TEST_ERROR(false, log->l_mp, XFS_ERRTAG_LOG_BAD_CRC)) {
 		iclog->ic_header.h_crc &= cpu_to_le32(0xAAAAAAAA);
-		iclog->ic_state |= XLOG_STATE_IOABORT;
+		iclog->ic_fail_crc = true;
 		xfs_warn(log->l_mp,
 	"Intentionally corrupted log record at LSN 0x%llx. Shutdown imminent.",
 			 be64_to_cpu(iclog->ic_header.h_lsn));
 	}
+#endif
 
 	bp->b_io_length = BTOBB(count);
 	bp->b_log_item = iclog;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 78a2abeba895..ac4bca257609 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -50,7 +50,6 @@ static inline uint xlog_get_client_id(__be32 i)
 #define XLOG_STATE_CALLBACK  0x0020 /* Callback functions now */
 #define XLOG_STATE_DIRTY     0x0040 /* Dirty IC log, not ready for ACTIVE status*/
 #define XLOG_STATE_IOERROR   0x0080 /* IO error happened in sync'ing log */
-#define XLOG_STATE_IOABORT   0x0100 /* force abort on I/O completion (debug) */
 #define XLOG_STATE_ALL	     0x7FFF /* All possible valid flags */
 #define XLOG_STATE_NOTUSED   0x8000 /* This IC log not being used */
 
@@ -223,6 +222,9 @@ typedef struct xlog_in_core {
 	atomic_t		ic_refcnt ____cacheline_aligned_in_smp;
 	xlog_in_core_2_t	*ic_data;
 #define ic_header	ic_data->hic_header
+#ifdef DEBUG
+	bool			ic_fail_crc : 1;
+#endif
 } xlog_in_core_t;
 
 /*
-- 
2.20.1

Re: [PATCH 08/24] xfs: remove XLOG_STATE_IOABORT

[Dave Chinner]

On Wed, Jun 05, 2019 at 09:14:55PM +0200, Christoph Hellwig wrote:
> This value is the only flag in ic_state, which we otherwise use as
> a state.  Switch it to a new debug-only field and also report and
> actual error in the buffer in the I/O completion path.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks fine to me.

Reviewed-by: Dave Chinner <dchinner@redhat.com>

-- 
Dave Chinner
david@fromorbit.com

[PATCH 09/24] xfs: don't use REQ_PREFLUSH for split log writes

[Christoph Hellwig]

If we have to split a log write because it wraps the end of the log we
can't just use REQ_PREFLUSH to flush before the first log write,
as the writes might get reordered somewhere in the I/O stack.  Issue
a manual flush in that case so that the ordering of the two log I/Os
doesn't matter.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 1af9302fbe1e..5c48b7de5033 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1904,7 +1904,7 @@ xlog_sync(
 	 * synchronously here; for an internal log we can simply use the block
 	 * layer state machine for preflushes.
 	 */
-	if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp)
+	if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp || split)
 		xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
 	else
 		bp->b_flags |= XBF_FLUSH;
-- 
2.20.1

[PATCH 10/24] xfs: factor out log buffer writing from xlog_sync

[Christoph Hellwig]

Replace the not very useful xlog_bdstrat wrapper with a new version that
that takes care of all the common logic for writing log buffers.  Use
the opportunity to avoid overloading the buffer address with the log
relative address, and to shed the unused return value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 125 +++++++++++++++++------------------------------
 1 file changed, 45 insertions(+), 80 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 5c48b7de5033..7b4a11c1ff08 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -45,10 +45,6 @@ STATIC int
 xlog_space_left(
 	struct xlog		*log,
 	atomic64_t		*head);
-STATIC int
-xlog_sync(
-	struct xlog		*log,
-	struct xlog_in_core	*iclog);
 STATIC void
 xlog_dealloc_log(
 	struct xlog		*log);
@@ -1726,28 +1722,34 @@ xlog_cksum(
 	return xfs_end_cksum(crc);
 }
 
-/*
- * The bdstrat callback function for log bufs. This gives us a central
- * place to trap bufs in case we get hit by a log I/O error and need to
- * shutdown. Actually, in practice, even when we didn't get a log error,
- * we transition the iclogs to IOERROR state *after* flushing all existing
- * iclogs to disk. This is because we don't want anymore new transactions to be
- * started or completed afterwards.
- *
- * We lock the iclogbufs here so that we can serialise against IO completion
- * during unmount. We might be processing a shutdown triggered during unmount,
- * and that can occur asynchronously to the unmount thread, and hence we need to
- * ensure that completes before tearing down the iclogbufs. Hence we need to
- * hold the buffer lock across the log IO to acheive that.
- */
-STATIC int
-xlog_bdstrat(
-	struct xfs_buf		*bp)
+STATIC void
+xlog_write_iclog(
+	struct xlog		*log,
+	struct xlog_in_core	*iclog,
+	struct xfs_buf		*bp,
+	uint64_t		bno,
+	bool			need_flush)
 {
-	struct xlog_in_core	*iclog = bp->b_log_item;
+	ASSERT(bno < log->l_logBBsize);
+	ASSERT(bno + bp->b_io_length <= log->l_logBBsize);
 
+	bp->b_maps[0].bm_bn = log->l_logBBstart + bno;
+	bp->b_log_item = iclog;
+	bp->b_flags &= ~XBF_FLUSH;
+	bp->b_flags |= (XBF_ASYNC | XBF_SYNCIO | XBF_WRITE | XBF_FUA);
+	if (need_flush)
+		bp->b_flags |= XBF_FLUSH;
+
+	/*
+	 * We lock the iclogbufs here so that we can serialise against I/O
+	 * completion during unmount.  We might be processing a shutdown
+	 * triggered during unmount, and that can occur asynchronously to the
+	 * unmount thread, and hence we need to ensure that completes before
+	 * tearing down the iclogbufs.  Hence we need to hold the buffer lock
+	 * across the log IO to archieve that.
+	 */
 	xfs_buf_lock(bp);
-	if (iclog->ic_state & XLOG_STATE_IOERROR) {
+	if (unlikely(iclog->ic_state & XLOG_STATE_IOERROR)) {
 		xfs_buf_ioerror(bp, -EIO);
 		xfs_buf_stale(bp);
 		xfs_buf_ioend(bp);
@@ -1757,11 +1759,10 @@ xlog_bdstrat(
 		 * doing it here. Similarly, IO completion will unlock the
 		 * buffer, so we don't do it here.
 		 */
-		return 0;
+		return;
 	}
 
 	xfs_buf_submit(bp);
-	return 0;
 }
 
 /*
@@ -1784,25 +1785,23 @@ xlog_bdstrat(
  * log will require grabbing the lock though.
  *
  * The entire log manager uses a logical block numbering scheme.  Only
- * log_sync (and then only bwrite()) know about the fact that the log may
- * not start with block zero on a given device.  The log block start offset
- * is added immediately before calling bwrite().
+ * xlog_write_iclog knows about the fact that the log may not start with
+ * block zero on a given device.
  */
-
-STATIC int
+STATIC void
 xlog_sync(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog)
 {
-	xfs_buf_t	*bp;
 	int		i;
 	uint		count;		/* byte count of bwrite */
 	uint		count_init;	/* initial count before roundup */
 	int		roundoff;       /* roundoff to BB or stripe */
 	int		split = 0;	/* split write into two regions */
-	int		error;
 	int		v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);
+	uint64_t	bno;
 	int		size;
+	bool		need_flush = true;
 
 	XFS_STATS_INC(log->l_mp, xs_log_writes);
 	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
@@ -1838,17 +1837,16 @@ xlog_sync(
 		size += roundoff;
 	iclog->ic_header.h_len = cpu_to_be32(size);
 
-	bp = iclog->ic_bp;
-	XFS_BUF_SET_ADDR(bp, BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn)));
-
 	XFS_STATS_ADD(log->l_mp, xs_log_blocks, BTOBB(count));
 
+	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));
+
 	/* Do we need to split this write into 2 parts? */
-	if (XFS_BUF_ADDR(bp) + BTOBB(count) > log->l_logBBsize) {
+	if (bno + BTOBB(count) > log->l_logBBsize) {
 		char		*dptr;
 
-		split = count - (BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp)));
-		count = BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp));
+		split = count - (BBTOB(log->l_logBBsize - bno));
+		count = BBTOB(log->l_logBBsize - bno);
 		iclog->ic_bwritecnt = 2;
 
 		/*
@@ -1891,11 +1889,6 @@ xlog_sync(
 	}
 #endif
 
-	bp->b_io_length = BTOBB(count);
-	bp->b_log_item = iclog;
-	bp->b_flags &= ~XBF_FLUSH;
-	bp->b_flags |= (XBF_ASYNC | XBF_SYNCIO | XBF_WRITE | XBF_FUA);
-
 	/*
 	 * Flush the data device before flushing the log to make sure all meta
 	 * data written back from the AIL actually made it to disk before
@@ -1904,50 +1897,22 @@ xlog_sync(
 	 * synchronously here; for an internal log we can simply use the block
 	 * layer state machine for preflushes.
 	 */
-	if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp || split)
+	if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp || split) {
 		xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
-	else
-		bp->b_flags |= XBF_FLUSH;
+		need_flush = false;
+	}
 
-	ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
-	ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
+	iclog->ic_bp->b_io_length = BTOBB(count);
 
 	xlog_verify_iclog(log, iclog, count, true);
+	xlog_write_iclog(log, iclog, iclog->ic_bp, bno, need_flush);
 
-	/* account for log which doesn't start at block #0 */
-	XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
-
-	/*
-	 * Don't call xfs_bwrite here. We do log-syncs even when the filesystem
-	 * is shutting down.
-	 */
-	error = xlog_bdstrat(bp);
-	if (error) {
-		xfs_buf_ioerror_alert(bp, "xlog_sync");
-		return error;
-	}
 	if (split) {
-		bp = iclog->ic_log->l_xbuf;
-		XFS_BUF_SET_ADDR(bp, 0);	     /* logical 0 */
-		xfs_buf_associate_memory(bp,
+		xfs_buf_associate_memory(iclog->ic_log->l_xbuf,
 				(char *)&iclog->ic_header + count, split);
-		bp->b_log_item = iclog;
-		bp->b_flags &= ~XBF_FLUSH;
-		bp->b_flags |= (XBF_ASYNC | XBF_SYNCIO | XBF_WRITE | XBF_FUA);
-
-		ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
-		ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
-
-		/* account for internal log which doesn't start at block #0 */
-		XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
-		error = xlog_bdstrat(bp);
-		if (error) {
-			xfs_buf_ioerror_alert(bp, "xlog_sync (split)");
-			return error;
-		}
+		xlog_write_iclog(log, iclog, iclog->ic_log->l_xbuf, 0, false);
 	}
-	return 0;
-}	/* xlog_sync */
+}
 
 /*
  * Deallocate a log structure
@@ -3187,7 +3152,7 @@ xlog_state_release_iclog(
 	 * flags after this point.
 	 */
 	if (sync)
-		return xlog_sync(log, iclog);
+		xlog_sync(log, iclog);
 	return 0;
 }	/* xlog_state_release_iclog */
 
-- 
2.20.1

[PATCH 11/24] xfs: factor out splitting of an iclog from xlog_sync

[Christoph Hellwig]

Split out a self-contained chunk of code from xlog_sync that calculates
the split offset for an iclog that wraps the log end and bumps the
cycles for the second half.

Use the chance to bring some sanity to the variables used to track the
split in xlog_sync by not changing the count variable, and instead use
split as the offset for the split and use those to calculate the
sizes and offsets for the two write buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 63 +++++++++++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 7b4a11c1ff08..2138bc8cc6e8 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1765,6 +1765,32 @@ xlog_write_iclog(
 	xfs_buf_submit(bp);
 }
 
+/*
+ * We need to bump cycle number for the part of the iclog that is
+ * written to the start of the log. Watch out for the header magic
+ * number case, though.
+ */
+static unsigned int
+xlog_split_iclog(
+	struct xlog		*log,
+	void			*data,
+	uint64_t		bno,
+	unsigned int		count)
+{
+	unsigned int		split_offset = BBTOB(log->l_logBBsize - bno);
+	unsigned int		i;
+
+	for (i = split_offset; i < count; i += BBSIZE) {
+		uint32_t cycle = get_unaligned_be32(data + i);
+
+		if (++cycle == XLOG_HEADER_MAGIC_NUM)
+			cycle++;
+		put_unaligned_be32(cycle, data + i);
+	}
+
+	return split_offset;
+}
+
 /*
  * Flush out the in-core log (iclog) to the on-disk log in an asynchronous 
  * fashion.  Previously, we should have moved the current iclog
@@ -1793,13 +1819,12 @@ xlog_sync(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog)
 {
-	int		i;
 	uint		count;		/* byte count of bwrite */
 	uint		count_init;	/* initial count before roundup */
 	int		roundoff;       /* roundoff to BB or stripe */
-	int		split = 0;	/* split write into two regions */
 	int		v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);
 	uint64_t	bno;
+	unsigned int	split = 0;
 	int		size;
 	bool		need_flush = true;
 
@@ -1842,32 +1867,8 @@ xlog_sync(
 	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));
 
 	/* Do we need to split this write into 2 parts? */
-	if (bno + BTOBB(count) > log->l_logBBsize) {
-		char		*dptr;
-
-		split = count - (BBTOB(log->l_logBBsize - bno));
-		count = BBTOB(log->l_logBBsize - bno);
-		iclog->ic_bwritecnt = 2;
-
-		/*
-		 * Bump the cycle numbers at the start of each block in the
-		 * part of the iclog that ends up in the buffer that gets
-		 * written to the start of the log.
-		 *
-		 * Watch out for the header magic number case, though.
-		 */
-		dptr = (char *)&iclog->ic_header + count;
-		for (i = 0; i < split; i += BBSIZE) {
-			uint32_t cycle = be32_to_cpu(*(__be32 *)dptr);
-			if (++cycle == XLOG_HEADER_MAGIC_NUM)
-				cycle++;
-			*(__be32 *)dptr = cpu_to_be32(cycle);
-
-			dptr += BBSIZE;
-		}
-	} else {
-		iclog->ic_bwritecnt = 1;
-	}
+	if (bno + BTOBB(count) > log->l_logBBsize)
+		split = xlog_split_iclog(log, &iclog->ic_header, bno, count);
 
 	/* calculcate the checksum */
 	iclog->ic_header.h_crc = xlog_cksum(log, &iclog->ic_header,
@@ -1902,14 +1903,16 @@ xlog_sync(
 		need_flush = false;
 	}
 
-	iclog->ic_bp->b_io_length = BTOBB(count);
+	iclog->ic_bp->b_io_length = BTOBB(split ? split : count);
+	iclog->ic_bwritecnt = split ? 2 : 1;
 
 	xlog_verify_iclog(log, iclog, count, true);
 	xlog_write_iclog(log, iclog, iclog->ic_bp, bno, need_flush);
 
 	if (split) {
 		xfs_buf_associate_memory(iclog->ic_log->l_xbuf,
-				(char *)&iclog->ic_header + count, split);
+				(char *)&iclog->ic_header + split,
+				count - split);
 		xlog_write_iclog(log, iclog, iclog->ic_log->l_xbuf, 0, false);
 	}
 }
-- 
2.20.1

[PATCH 12/24] xfs: factor out iclog size calculation from xlog_sync

[Christoph Hellwig]

Split out another self-contained bit of code from xlog_sync.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 67 +++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 26 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 2138bc8cc6e8..b22f75affdc5 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1791,6 +1791,39 @@ xlog_split_iclog(
 	return split_offset;
 }
 
+static int
+xlog_calc_iclog_size(
+	struct xlog		*log,
+	struct xlog_in_core	*iclog,
+	uint32_t		*roundoff)
+{
+	uint32_t		count_init, count;
+	bool			use_lsunit;
+
+	use_lsunit = xfs_sb_version_haslogv2(&log->l_mp->m_sb) &&
+			log->l_mp->m_sb.sb_logsunit > 1;
+
+	/* Add for LR header */
+	count_init = log->l_iclog_hsize + iclog->ic_offset;
+
+	/* Round out the log write size */
+	if (use_lsunit) {
+		/* we have a v2 stripe unit to use */
+		count = XLOG_LSUNITTOB(log, XLOG_BTOLSUNIT(log, count_init));
+	} else {
+		count = BBTOB(BTOBB(count_init));
+	}
+
+	ASSERT(count >= count_init);
+	*roundoff = count - count_init;
+
+	if (use_lsunit)
+		ASSERT(*roundoff < log->l_mp->m_sb.sb_logsunit);
+	else
+		ASSERT(*roundoff < BBTOB(1));
+	return count;
+}
+
 /*
  * Flush out the in-core log (iclog) to the on-disk log in an asynchronous 
  * fashion.  Previously, we should have moved the current iclog
@@ -1819,35 +1852,17 @@ xlog_sync(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog)
 {
-	uint		count;		/* byte count of bwrite */
-	uint		count_init;	/* initial count before roundup */
-	int		roundoff;       /* roundoff to BB or stripe */
-	int		v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);
-	uint64_t	bno;
-	unsigned int	split = 0;
-	int		size;
-	bool		need_flush = true;
+	unsigned int		count;		/* byte count of bwrite */
+	unsigned int		roundoff;       /* roundoff to BB or stripe */
+	uint64_t		bno;
+	unsigned int		split = 0;
+	unsigned int		size;
+	bool			need_flush = true;
 
 	XFS_STATS_INC(log->l_mp, xs_log_writes);
 	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
 
-	/* Add for LR header */
-	count_init = log->l_iclog_hsize + iclog->ic_offset;
-
-	/* Round out the log write size */
-	if (v2 && log->l_mp->m_sb.sb_logsunit > 1) {
-		/* we have a v2 stripe unit to use */
-		count = XLOG_LSUNITTOB(log, XLOG_BTOLSUNIT(log, count_init));
-	} else {
-		count = BBTOB(BTOBB(count_init));
-	}
-	roundoff = count - count_init;
-	ASSERT(roundoff >= 0);
-	ASSERT((v2 && log->l_mp->m_sb.sb_logsunit > 1 && 
-                roundoff < log->l_mp->m_sb.sb_logsunit)
-		|| 
-		(log->l_mp->m_sb.sb_logsunit <= 1 && 
-		 roundoff < BBTOB(1)));
+	count = xlog_calc_iclog_size(log, iclog, &roundoff);
 
 	/* move grant heads by roundoff in sync */
 	xlog_grant_add_space(log, &log->l_reserve_head.grant, roundoff);
@@ -1858,7 +1873,7 @@ xlog_sync(
 
 	/* real byte length */
 	size = iclog->ic_offset;
-	if (v2)
+	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb))
 		size += roundoff;
 	iclog->ic_header.h_len = cpu_to_be32(size);
 
-- 
2.20.1

[PATCH 13/24] xfs: update both stat counters together in xlog_sync

[Christoph Hellwig]

Just a small bit of code tidying up.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index b22f75affdc5..16f90a8fe49b 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1859,7 +1859,6 @@ xlog_sync(
 	unsigned int		size;
 	bool			need_flush = true;
 
-	XFS_STATS_INC(log->l_mp, xs_log_writes);
 	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
 
 	count = xlog_calc_iclog_size(log, iclog, &roundoff);
@@ -1877,6 +1876,7 @@ xlog_sync(
 		size += roundoff;
 	iclog->ic_header.h_len = cpu_to_be32(size);
 
+	XFS_STATS_INC(log->l_mp, xs_log_writes);
 	XFS_STATS_ADD(log->l_mp, xs_log_blocks, BTOBB(count));
 
 	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));
-- 
2.20.1

[PATCH 14/24] xfs: remove the syncing argument from xlog_verify_iclog

[Christoph Hellwig]

The only caller unconditionally passes true here.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 16f90a8fe49b..5f5b74c7ec2e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -103,8 +103,7 @@ STATIC void
 xlog_verify_iclog(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog,
-	int			count,
-	bool                    syncing);
+	int			count);
 STATIC void
 xlog_verify_tail_lsn(
 	struct xlog		*log,
@@ -113,7 +112,7 @@ xlog_verify_tail_lsn(
 #else
 #define xlog_verify_dest_ptr(a,b)
 #define xlog_verify_grant_tail(a)
-#define xlog_verify_iclog(a,b,c,d)
+#define xlog_verify_iclog(a,b,c)
 #define xlog_verify_tail_lsn(a,b,c)
 #endif
 
@@ -1921,7 +1920,7 @@ xlog_sync(
 	iclog->ic_bp->b_io_length = BTOBB(split ? split : count);
 	iclog->ic_bwritecnt = split ? 2 : 1;
 
-	xlog_verify_iclog(log, iclog, count, true);
+	xlog_verify_iclog(log, iclog, count);
 	xlog_write_iclog(log, iclog, iclog->ic_bp, bno, need_flush);
 
 	if (split) {
@@ -3761,8 +3760,7 @@ STATIC void
 xlog_verify_iclog(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog,
-	int			count,
-	bool                    syncing)
+	int			count)
 {
 	xlog_op_header_t	*ophead;
 	xlog_in_core_t		*icptr;
@@ -3806,7 +3804,7 @@ xlog_verify_iclog(
 		/* clientid is only 1 byte */
 		p = &ophead->oh_clientid;
 		field_offset = p - base_ptr;
-		if (!syncing || (field_offset & 0x1ff)) {
+		if (field_offset & 0x1ff) {
 			clientid = ophead->oh_clientid;
 		} else {
 			idx = BTOBBT((char *)&ophead->oh_clientid - iclog->ic_datap);
@@ -3829,7 +3827,7 @@ xlog_verify_iclog(
 		/* check length */
 		p = &ophead->oh_len;
 		field_offset = p - base_ptr;
-		if (!syncing || (field_offset & 0x1ff)) {
+		if (field_offset & 0x1ff) {
 			op_len = be32_to_cpu(ophead->oh_len);
 		} else {
 			idx = BTOBBT((uintptr_t)&ophead->oh_len -
-- 
2.20.1

[PATCH 15/24] xfs: make use of the l_targ field in struct xlog

[Christoph Hellwig]

Use the slightly shorter way to get at the buftarg for the log device
wherever we can in the log and log recovery code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c         | 6 +++---
 fs/xfs/xfs_log_recover.c | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 5f5b74c7ec2e..452d03898fd0 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -927,7 +927,7 @@ xfs_log_unmount_write(xfs_mount_t *mp)
 	 * Or, if we are doing a forced umount (typically because of IO errors).
 	 */
 	if (mp->m_flags & XFS_MOUNT_NORECOVERY ||
-	    xfs_readonly_buftarg(log->l_mp->m_logdev_targp)) {
+	    xfs_readonly_buftarg(log->l_targ)) {
 		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
 		return 0;
 	}
@@ -1442,7 +1442,7 @@ xlog_alloc_log(
 	 * having set it up properly.
 	 */
 	error = -ENOMEM;
-	bp = xfs_buf_alloc(mp->m_logdev_targp, XFS_BUF_DADDR_NULL,
+	bp = xfs_buf_alloc(log->l_targ, XFS_BUF_DADDR_NULL,
 			   BTOBB(log->l_iclog_size), XBF_NO_IOACCT);
 	if (!bp)
 		goto out_free_log;
@@ -1912,7 +1912,7 @@ xlog_sync(
 	 * synchronously here; for an internal log we can simply use the block
 	 * layer state machine for preflushes.
 	 */
-	if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp || split) {
+	if (log->l_targ != log->l_mp->m_ddev_targp || split) {
 		xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
 		need_flush = false;
 	}
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 9329f5adbfbe..4139b907e9cd 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -134,7 +134,7 @@ xlog_get_bp(
 		nbblks += log->l_sectBBsize;
 	nbblks = round_up(nbblks, log->l_sectBBsize);
 
-	bp = xfs_buf_get_uncached(log->l_mp->m_logdev_targp, nbblks, 0);
+	bp = xfs_buf_get_uncached(log->l_targ, nbblks, 0);
 	if (bp)
 		xfs_buf_unlock(bp);
 	return bp;
@@ -1505,7 +1505,7 @@ xlog_find_tail(
 	 * But... if the -device- itself is readonly, just skip this.
 	 * We can't recover this device anyway, so it won't matter.
 	 */
-	if (!xfs_readonly_buftarg(log->l_mp->m_logdev_targp))
+	if (!xfs_readonly_buftarg(log->l_targ))
 		error = xlog_clear_stale_blocks(log, tail_lsn);
 
 done:
-- 
2.20.1

[PATCH 16/24] xfs: use bios directly to write log buffers

[Christoph Hellwig]

Currently the XFS logging code uses the xfs_buf structure and
associated APIs to write the log buffers to disk.  This requires
various special cases in the log code and is generally not very
optimal.

Instead of using a buffer just allocate a kmem_alloc_larger region for
each log buffer, and use a bio and bio_vec array embedded in the iclog
structure to write the buffer to disk.  This also allows for using
the bio split and chaining case to deal with the case of a log
buffer wrapping around the end of the log.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c      | 231 ++++++++++++++++++++----------------------
 fs/xfs/xfs_log_priv.h |  18 ++--
 2 files changed, 119 insertions(+), 130 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 452d03898fd0..0a8a43d77385 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1239,32 +1239,30 @@ xlog_space_left(
 }
 
 
-/*
- * Log function which is called when an io completes.
- *
- * The log manager needs its own routine, in order to control what
- * happens with the buffer after the write completes.
- */
 static void
-xlog_iodone(xfs_buf_t *bp)
+xlog_ioend_work(
+	struct work_struct	*work)
 {
-	struct xlog_in_core	*iclog = bp->b_log_item;
-	struct xlog		*l = iclog->ic_log;
+	struct xlog_in_core     *iclog =
+		container_of(work, struct xlog_in_core, ic_end_io_work);
+	struct xlog		*log = iclog->ic_log;
 	int			aborted = 0;
+	int			error;
 
 #ifdef DEBUG
 	/* treat writes with injected CRC errors as failed */
 	if (iclog->ic_fail_crc)
-		bp->b_error = -EIO;
+		error = -EIO;
+	else
 #endif
+		error = blk_status_to_errno(iclog->ic_bio.bi_status);
 
 	/*
 	 * Race to shutdown the filesystem if we see an error.
 	 */
-	if (XFS_TEST_ERROR(bp->b_error, l->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
-		xfs_buf_ioerror_alert(bp, __func__);
-		xfs_buf_stale(bp);
-		xfs_force_shutdown(l->l_mp, SHUTDOWN_LOG_IO_ERROR);
+	if (XFS_TEST_ERROR(error, log->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
+		xfs_alert(log->l_mp, "log I/O error %d", error);
+		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
 		/*
 		 * This flag will be propagated to the trans-committed
 		 * callback routines to let them know that the log-commit
@@ -1275,17 +1273,16 @@ xlog_iodone(xfs_buf_t *bp)
 		aborted = XFS_LI_ABORTED;
 	}
 
-	/* log I/O is always issued ASYNC */
-	ASSERT(bp->b_flags & XBF_ASYNC);
 	xlog_state_done_syncing(iclog, aborted);
+	bio_uninit(&iclog->ic_bio);
 
 	/*
-	 * drop the buffer lock now that we are done. Nothing references
-	 * the buffer after this, so an unmount waiting on this lock can now
-	 * tear it down safely. As such, it is unsafe to reference the buffer
-	 * (bp) after the unlock as we could race with it being freed.
+	 * Drop the lock to signal that we are done. Nothing references the
+	 * iclog after this, so an unmount waiting on this lock can now tear it
+	 * down safely. As such, it is unsafe to reference the iclog after the
+	 * unlock as we could race with it being freed.
 	 */
-	xfs_buf_unlock(bp);
+	up(&iclog->ic_sema);
 }
 
 /*
@@ -1378,7 +1375,6 @@ xlog_alloc_log(
 	xlog_rec_header_t	*head;
 	xlog_in_core_t		**iclogp;
 	xlog_in_core_t		*iclog, *prev_iclog=NULL;
-	xfs_buf_t		*bp;
 	int			i;
 	int			error = -ENOMEM;
 	uint			log2_size = 0;
@@ -1436,30 +1432,6 @@ xlog_alloc_log(
 
 	xlog_get_iclog_buffer_size(mp, log);
 
-	/*
-	 * Use a NULL block for the extra log buffer used during splits so that
-	 * it will trigger errors if we ever try to do IO on it without first
-	 * having set it up properly.
-	 */
-	error = -ENOMEM;
-	bp = xfs_buf_alloc(log->l_targ, XFS_BUF_DADDR_NULL,
-			   BTOBB(log->l_iclog_size), XBF_NO_IOACCT);
-	if (!bp)
-		goto out_free_log;
-
-	/*
-	 * The iclogbuf buffer locks are held over IO but we are not going to do
-	 * IO yet.  Hence unlock the buffer so that the log IO path can grab it
-	 * when appropriately.
-	 */
-	ASSERT(xfs_buf_islocked(bp));
-	xfs_buf_unlock(bp);
-
-	/* use high priority wq for log I/O completion */
-	bp->b_ioend_wq = mp->m_log_workqueue;
-	bp->b_iodone = xlog_iodone;
-	log->l_xbuf = bp;
-
 	spin_lock_init(&log->l_icloglock);
 	init_waitqueue_head(&log->l_flush_wait);
 
@@ -1472,29 +1444,21 @@ xlog_alloc_log(
 	 * xlog_in_core_t in xfs_log_priv.h for details.
 	 */
 	ASSERT(log->l_iclog_size >= 4096);
-	for (i=0; i < log->l_iclog_bufs; i++) {
-		*iclogp = kmem_zalloc(sizeof(xlog_in_core_t), KM_MAYFAIL);
-		if (!*iclogp)
+	for (i = 0; i < log->l_iclog_bufs; i++) {
+		size_t bvec_size = howmany(log->l_iclog_size, PAGE_SIZE);
+
+		iclog = kmem_zalloc(sizeof(*iclog) + bvec_size, KM_MAYFAIL);
+		if (!iclog)
 			goto out_free_iclog;
 
-		iclog = *iclogp;
+		*iclogp = iclog;
 		iclog->ic_prev = prev_iclog;
 		prev_iclog = iclog;
 
-		bp = xfs_buf_get_uncached(mp->m_logdev_targp,
-					  BTOBB(log->l_iclog_size),
-					  XBF_NO_IOACCT);
-		if (!bp)
+		iclog->ic_data = kmem_alloc_large(log->l_iclog_size,
+				KM_MAYFAIL);
+		if (!iclog->ic_data)
 			goto out_free_iclog;
-
-		ASSERT(xfs_buf_islocked(bp));
-		xfs_buf_unlock(bp);
-
-		/* use high priority wq for log I/O completion */
-		bp->b_ioend_wq = mp->m_log_workqueue;
-		bp->b_iodone = xlog_iodone;
-		iclog->ic_bp = bp;
-		iclog->ic_data = bp->b_addr;
 #ifdef DEBUG
 		log->l_iclog_bak[i] = &iclog->ic_header;
 #endif
@@ -1508,7 +1472,7 @@ xlog_alloc_log(
 		head->h_fmt = cpu_to_be32(XLOG_FMT);
 		memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));
 
-		iclog->ic_size = BBTOB(bp->b_length) - log->l_iclog_hsize;
+		iclog->ic_size = log->l_iclog_size - log->l_iclog_hsize;
 		iclog->ic_state = XLOG_STATE_ACTIVE;
 		iclog->ic_log = log;
 		atomic_set(&iclog->ic_refcnt, 0);
@@ -1518,6 +1482,8 @@ xlog_alloc_log(
 
 		init_waitqueue_head(&iclog->ic_force_wait);
 		init_waitqueue_head(&iclog->ic_write_wait);
+		INIT_WORK(&iclog->ic_end_io_work, xlog_ioend_work);
+		sema_init(&iclog->ic_sema, 1);
 
 		iclogp = &iclog->ic_next;
 	}
@@ -1532,11 +1498,9 @@ xlog_alloc_log(
 out_free_iclog:
 	for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
 		prev_iclog = iclog->ic_next;
-		if (iclog->ic_bp)
-			xfs_buf_free(iclog->ic_bp);
+		kmem_free(iclog->ic_data);
 		kmem_free(iclog);
 	}
-	xfs_buf_free(log->l_xbuf);
 out_free_log:
 	kmem_free(log);
 out:
@@ -1721,23 +1685,43 @@ xlog_cksum(
 	return xfs_end_cksum(crc);
 }
 
+static void
+xlog_bio_end_io(
+	struct bio		*bio)
+{
+	struct xlog_in_core	*iclog = bio->bi_private;
+
+	queue_work(iclog->ic_log->l_mp->m_log_workqueue,
+		   &iclog->ic_end_io_work);
+}
+
+static void
+xlog_map_iclog_data(
+	struct bio		*bio,
+	void			*data,
+	size_t			count)
+{
+	do {
+		struct page	*page = kmem_to_page(data);
+		unsigned int	off = offset_in_page(data);
+		size_t		len = min_t(size_t, count, PAGE_SIZE - off);
+
+		WARN_ON_ONCE(bio_add_page(bio, page, len, off) != len);
+
+		data += len;
+		count -= len;
+	} while (count);
+}
+
 STATIC void
 xlog_write_iclog(
 	struct xlog		*log,
 	struct xlog_in_core	*iclog,
-	struct xfs_buf		*bp,
 	uint64_t		bno,
+	unsigned int		count,
 	bool			need_flush)
 {
 	ASSERT(bno < log->l_logBBsize);
-	ASSERT(bno + bp->b_io_length <= log->l_logBBsize);
-
-	bp->b_maps[0].bm_bn = log->l_logBBstart + bno;
-	bp->b_log_item = iclog;
-	bp->b_flags &= ~XBF_FLUSH;
-	bp->b_flags |= (XBF_ASYNC | XBF_SYNCIO | XBF_WRITE | XBF_FUA);
-	if (need_flush)
-		bp->b_flags |= XBF_FLUSH;
 
 	/*
 	 * We lock the iclogbufs here so that we can serialise against I/O
@@ -1747,21 +1731,52 @@ xlog_write_iclog(
 	 * tearing down the iclogbufs.  Hence we need to hold the buffer lock
 	 * across the log IO to archieve that.
 	 */
-	xfs_buf_lock(bp);
+	down(&iclog->ic_sema);
 	if (unlikely(iclog->ic_state & XLOG_STATE_IOERROR)) {
-		xfs_buf_ioerror(bp, -EIO);
-		xfs_buf_stale(bp);
-		xfs_buf_ioend(bp);
 		/*
 		 * It would seem logical to return EIO here, but we rely on
 		 * the log state machine to propagate I/O errors instead of
-		 * doing it here. Similarly, IO completion will unlock the
-		 * buffer, so we don't do it here.
+		 * doing it here.  We kick of the state machine and unlock
+		 * the buffer manually, the code needs to be kept in sync
+		 * with the I/O completion path.
 		 */
+		xlog_state_done_syncing(iclog, XFS_LI_ABORTED);
+		up(&iclog->ic_sema);
 		return;
 	}
 
-	xfs_buf_submit(bp);
+	iclog->ic_io_size = count;
+
+	bio_init(&iclog->ic_bio, iclog->ic_bvec, howmany(count, PAGE_SIZE));
+	bio_set_dev(&iclog->ic_bio, log->l_targ->bt_bdev);
+	iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart + bno;
+	iclog->ic_bio.bi_end_io = xlog_bio_end_io;
+	iclog->ic_bio.bi_private = iclog;
+	iclog->ic_bio.bi_opf = REQ_OP_WRITE | REQ_META | REQ_SYNC | REQ_FUA;
+	if (need_flush)
+		iclog->ic_bio.bi_opf |= REQ_PREFLUSH;
+
+	xlog_map_iclog_data(&iclog->ic_bio, iclog->ic_data, iclog->ic_io_size);
+	if (is_vmalloc_addr(iclog->ic_data))
+		flush_kernel_vmap_range(iclog->ic_data, iclog->ic_io_size);
+
+	/*
+	 * If this log buffer would straddle the end of the log we will have
+	 * to split it up into two bios, so that we can continue at the start.
+	 */
+	if (bno + BTOBB(count) > log->l_logBBsize) {
+		struct bio *split;
+
+		split = bio_split(&iclog->ic_bio, log->l_logBBsize - bno,
+				  GFP_NOIO, &fs_bio_set);
+		bio_chain(split, &iclog->ic_bio);
+		submit_bio(split);
+
+		/* restart at logical offset zero for the remainder */
+		iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart;
+	}
+
+	submit_bio(&iclog->ic_bio);
 }
 
 /*
@@ -1769,7 +1784,7 @@ xlog_write_iclog(
  * written to the start of the log. Watch out for the header magic
  * number case, though.
  */
-static unsigned int
+static void
 xlog_split_iclog(
 	struct xlog		*log,
 	void			*data,
@@ -1786,8 +1801,6 @@ xlog_split_iclog(
 			cycle++;
 		put_unaligned_be32(cycle, data + i);
 	}
-
-	return split_offset;
 }
 
 static int
@@ -1854,9 +1867,8 @@ xlog_sync(
 	unsigned int		count;		/* byte count of bwrite */
 	unsigned int		roundoff;       /* roundoff to BB or stripe */
 	uint64_t		bno;
-	unsigned int		split = 0;
 	unsigned int		size;
-	bool			need_flush = true;
+	bool			need_flush = true, split = false;
 
 	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
 
@@ -1881,8 +1893,10 @@ xlog_sync(
 	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));
 
 	/* Do we need to split this write into 2 parts? */
-	if (bno + BTOBB(count) > log->l_logBBsize)
-		split = xlog_split_iclog(log, &iclog->ic_header, bno, count);
+	if (bno + BTOBB(count) > log->l_logBBsize) {
+		xlog_split_iclog(log, &iclog->ic_header, bno, count);
+		split = true;
+	}
 
 	/* calculcate the checksum */
 	iclog->ic_header.h_crc = xlog_cksum(log, &iclog->ic_header,
@@ -1917,18 +1931,8 @@ xlog_sync(
 		need_flush = false;
 	}
 
-	iclog->ic_bp->b_io_length = BTOBB(split ? split : count);
-	iclog->ic_bwritecnt = split ? 2 : 1;
-
 	xlog_verify_iclog(log, iclog, count);
-	xlog_write_iclog(log, iclog, iclog->ic_bp, bno, need_flush);
-
-	if (split) {
-		xfs_buf_associate_memory(iclog->ic_log->l_xbuf,
-				(char *)&iclog->ic_header + split,
-				count - split);
-		xlog_write_iclog(log, iclog, iclog->ic_log->l_xbuf, 0, false);
-	}
+	xlog_write_iclog(log, iclog, bno, count, need_flush);
 }
 
 /*
@@ -1949,25 +1953,15 @@ xlog_dealloc_log(
 	 */
 	iclog = log->l_iclog;
 	for (i = 0; i < log->l_iclog_bufs; i++) {
-		xfs_buf_lock(iclog->ic_bp);
-		xfs_buf_unlock(iclog->ic_bp);
+		down(&iclog->ic_sema);
+		up(&iclog->ic_sema);
 		iclog = iclog->ic_next;
 	}
 
-	/*
-	 * Always need to ensure that the extra buffer does not point to memory
-	 * owned by another log buffer before we free it. Also, cycle the lock
-	 * first to ensure we've completed IO on it.
-	 */
-	xfs_buf_lock(log->l_xbuf);
-	xfs_buf_unlock(log->l_xbuf);
-	xfs_buf_set_empty(log->l_xbuf, BTOBB(log->l_iclog_size));
-	xfs_buf_free(log->l_xbuf);
-
 	iclog = log->l_iclog;
 	for (i = 0; i < log->l_iclog_bufs; i++) {
-		xfs_buf_free(iclog->ic_bp);
 		next_iclog = iclog->ic_next;
+		kmem_free(iclog->ic_data);
 		kmem_free(iclog);
 		iclog = next_iclog;
 	}
@@ -2885,8 +2879,6 @@ xlog_state_done_syncing(
 	ASSERT(iclog->ic_state == XLOG_STATE_SYNCING ||
 	       iclog->ic_state == XLOG_STATE_IOERROR);
 	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
-	ASSERT(iclog->ic_bwritecnt == 1 || iclog->ic_bwritecnt == 2);
-
 
 	/*
 	 * If we got an error, either on the first buffer, or in the case of
@@ -2894,13 +2886,8 @@ xlog_state_done_syncing(
 	 * and none should ever be attempted to be written to disk
 	 * again.
 	 */
-	if (iclog->ic_state != XLOG_STATE_IOERROR) {
-		if (--iclog->ic_bwritecnt == 1) {
-			spin_unlock(&log->l_icloglock);
-			return;
-		}
+	if (iclog->ic_state != XLOG_STATE_IOERROR)
 		iclog->ic_state = XLOG_STATE_DONE_SYNC;
-	}
 
 	/*
 	 * Someone could be sleeping prior to writing out the next
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index ac4bca257609..b9c90abb09a2 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -178,11 +178,12 @@ typedef struct xlog_ticket {
  *	the iclog.
  * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
  * - ic_next is the pointer to the next iclog in the ring.
- * - ic_bp is a pointer to the buffer used to write this incore log to disk.
  * - ic_log is a pointer back to the global log structure.
  * - ic_callback is a linked list of callback function/argument pairs to be
  *	called after an iclog finishes writing.
- * - ic_size is the full size of the header plus data.
+ * - ic_size is the full size of the log buffer, minus the cycle headers.
+ * - ic_io_size is the size of the currently pending log buffer write, which
+ *	might be smaller than ic_size
  * - ic_offset is the current number of bytes written to in this iclog.
  * - ic_refcnt is bumped when someone is writing to the log.
  * - ic_state is the state of the iclog.
@@ -205,11 +206,10 @@ typedef struct xlog_in_core {
 	wait_queue_head_t	ic_write_wait;
 	struct xlog_in_core	*ic_next;
 	struct xlog_in_core	*ic_prev;
-	struct xfs_buf		*ic_bp;
 	struct xlog		*ic_log;
-	int			ic_size;
-	int			ic_offset;
-	int			ic_bwritecnt;
+	u32			ic_size;
+	u32			ic_io_size;
+	u32			ic_offset;
 	unsigned short		ic_state;
 	char			*ic_datap;	/* pointer to iclog data */
 
@@ -225,6 +225,10 @@ typedef struct xlog_in_core {
 #ifdef DEBUG
 	bool			ic_fail_crc : 1;
 #endif
+	struct semaphore	ic_sema;
+	struct work_struct	ic_end_io_work;
+	struct bio		ic_bio;
+	struct bio_vec		ic_bvec[];
 } xlog_in_core_t;
 
 /*
@@ -352,8 +356,6 @@ struct xlog {
 	struct xfs_mount	*l_mp;	        /* mount point */
 	struct xfs_ail		*l_ailp;	/* AIL log is working with */
 	struct xfs_cil		*l_cilp;	/* CIL log is working with */
-	struct xfs_buf		*l_xbuf;        /* extra buffer for log
-						 * wrapping */
 	struct xfs_buftarg	*l_targ;        /* buftarg of log */
 	struct delayed_work	l_work;		/* background flush work */
 	uint			l_flags;
-- 
2.20.1

Re: [PATCH 16/24] xfs: use bios directly to write log buffers

[Darrick J. Wong]

On Wed, Jun 05, 2019 at 09:15:03PM +0200, Christoph Hellwig wrote:
> Currently the XFS logging code uses the xfs_buf structure and
> associated APIs to write the log buffers to disk.  This requires
> various special cases in the log code and is generally not very
> optimal.
> 
> Instead of using a buffer just allocate a kmem_alloc_larger region for
> each log buffer, and use a bio and bio_vec array embedded in the iclog
> structure to write the buffer to disk.  This also allows for using
> the bio split and chaining case to deal with the case of a log
> buffer wrapping around the end of the log.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_log.c      | 231 ++++++++++++++++++++----------------------
>  fs/xfs/xfs_log_priv.h |  18 ++--
>  2 files changed, 119 insertions(+), 130 deletions(-)
> 
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 452d03898fd0..0a8a43d77385 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1239,32 +1239,30 @@ xlog_space_left(
>  }
>  
>  
> -/*
> - * Log function which is called when an io completes.
> - *
> - * The log manager needs its own routine, in order to control what
> - * happens with the buffer after the write completes.
> - */
>  static void
> -xlog_iodone(xfs_buf_t *bp)
> +xlog_ioend_work(
> +	struct work_struct	*work)
>  {
> -	struct xlog_in_core	*iclog = bp->b_log_item;
> -	struct xlog		*l = iclog->ic_log;
> +	struct xlog_in_core     *iclog =
> +		container_of(work, struct xlog_in_core, ic_end_io_work);
> +	struct xlog		*log = iclog->ic_log;
>  	int			aborted = 0;
> +	int			error;
>  
>  #ifdef DEBUG
>  	/* treat writes with injected CRC errors as failed */
>  	if (iclog->ic_fail_crc)
> -		bp->b_error = -EIO;
> +		error = -EIO;
> +	else
>  #endif
> +		error = blk_status_to_errno(iclog->ic_bio.bi_status);

Ugh, I don't really like this awkwardly split else/#endif construction
here.  Can we simply do:

error = blk_status_to_errno(iclog->ic_bio.bi_status);

#ifdef DEBUG
if (iclog->ic_fail_crc)
	error = -EIO;
#endif

instead?

>  
>  	/*
>  	 * Race to shutdown the filesystem if we see an error.
>  	 */
> -	if (XFS_TEST_ERROR(bp->b_error, l->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
> -		xfs_buf_ioerror_alert(bp, __func__);
> -		xfs_buf_stale(bp);
> -		xfs_force_shutdown(l->l_mp, SHUTDOWN_LOG_IO_ERROR);
> +	if (XFS_TEST_ERROR(error, log->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
> +		xfs_alert(log->l_mp, "log I/O error %d", error);
> +		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
>  		/*
>  		 * This flag will be propagated to the trans-committed
>  		 * callback routines to let them know that the log-commit

<snip>

> @@ -1747,21 +1731,52 @@ xlog_write_iclog(
>  	 * tearing down the iclogbufs.  Hence we need to hold the buffer lock
>  	 * across the log IO to archieve that.
>  	 */
> -	xfs_buf_lock(bp);
> +	down(&iclog->ic_sema);
>  	if (unlikely(iclog->ic_state & XLOG_STATE_IOERROR)) {
> -		xfs_buf_ioerror(bp, -EIO);
> -		xfs_buf_stale(bp);
> -		xfs_buf_ioend(bp);
>  		/*
>  		 * It would seem logical to return EIO here, but we rely on
>  		 * the log state machine to propagate I/O errors instead of
> -		 * doing it here. Similarly, IO completion will unlock the
> -		 * buffer, so we don't do it here.
> +		 * doing it here.  We kick of the state machine and unlock
> +		 * the buffer manually, the code needs to be kept in sync
> +		 * with the I/O completion path.
>  		 */
> +		xlog_state_done_syncing(iclog, XFS_LI_ABORTED);
> +		up(&iclog->ic_sema);
>  		return;
>  	}
>  
> -	xfs_buf_submit(bp);
> +	iclog->ic_io_size = count;
> +
> +	bio_init(&iclog->ic_bio, iclog->ic_bvec, howmany(count, PAGE_SIZE));
> +	bio_set_dev(&iclog->ic_bio, log->l_targ->bt_bdev);
> +	iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart + bno;
> +	iclog->ic_bio.bi_end_io = xlog_bio_end_io;
> +	iclog->ic_bio.bi_private = iclog;
> +	iclog->ic_bio.bi_opf = REQ_OP_WRITE | REQ_META | REQ_SYNC | REQ_FUA;
> +	if (need_flush)
> +		iclog->ic_bio.bi_opf |= REQ_PREFLUSH;
> +
> +	xlog_map_iclog_data(&iclog->ic_bio, iclog->ic_data, iclog->ic_io_size);

/me is surprised you got all the way through that without making a
convenience variable, but I guess none of the lines overflow.

--D

> +	if (is_vmalloc_addr(iclog->ic_data))
> +		flush_kernel_vmap_range(iclog->ic_data, iclog->ic_io_size);
> +
> +	/*
> +	 * If this log buffer would straddle the end of the log we will have
> +	 * to split it up into two bios, so that we can continue at the start.
> +	 */
> +	if (bno + BTOBB(count) > log->l_logBBsize) {
> +		struct bio *split;
> +
> +		split = bio_split(&iclog->ic_bio, log->l_logBBsize - bno,
> +				  GFP_NOIO, &fs_bio_set);
> +		bio_chain(split, &iclog->ic_bio);
> +		submit_bio(split);
> +
> +		/* restart at logical offset zero for the remainder */
> +		iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart;
> +	}
> +
> +	submit_bio(&iclog->ic_bio);
>  }
>  
>  /*
> @@ -1769,7 +1784,7 @@ xlog_write_iclog(
>   * written to the start of the log. Watch out for the header magic
>   * number case, though.
>   */
> -static unsigned int
> +static void
>  xlog_split_iclog(
>  	struct xlog		*log,
>  	void			*data,
> @@ -1786,8 +1801,6 @@ xlog_split_iclog(
>  			cycle++;
>  		put_unaligned_be32(cycle, data + i);
>  	}
> -
> -	return split_offset;
>  }
>  
>  static int
> @@ -1854,9 +1867,8 @@ xlog_sync(
>  	unsigned int		count;		/* byte count of bwrite */
>  	unsigned int		roundoff;       /* roundoff to BB or stripe */
>  	uint64_t		bno;
> -	unsigned int		split = 0;
>  	unsigned int		size;
> -	bool			need_flush = true;
> +	bool			need_flush = true, split = false;
>  
>  	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
>  
> @@ -1881,8 +1893,10 @@ xlog_sync(
>  	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));
>  
>  	/* Do we need to split this write into 2 parts? */
> -	if (bno + BTOBB(count) > log->l_logBBsize)
> -		split = xlog_split_iclog(log, &iclog->ic_header, bno, count);
> +	if (bno + BTOBB(count) > log->l_logBBsize) {
> +		xlog_split_iclog(log, &iclog->ic_header, bno, count);
> +		split = true;
> +	}
>  
>  	/* calculcate the checksum */
>  	iclog->ic_header.h_crc = xlog_cksum(log, &iclog->ic_header,
> @@ -1917,18 +1931,8 @@ xlog_sync(
>  		need_flush = false;
>  	}
>  
> -	iclog->ic_bp->b_io_length = BTOBB(split ? split : count);
> -	iclog->ic_bwritecnt = split ? 2 : 1;
> -
>  	xlog_verify_iclog(log, iclog, count);
> -	xlog_write_iclog(log, iclog, iclog->ic_bp, bno, need_flush);
> -
> -	if (split) {
> -		xfs_buf_associate_memory(iclog->ic_log->l_xbuf,
> -				(char *)&iclog->ic_header + split,
> -				count - split);
> -		xlog_write_iclog(log, iclog, iclog->ic_log->l_xbuf, 0, false);
> -	}
> +	xlog_write_iclog(log, iclog, bno, count, need_flush);
>  }
>  
>  /*
> @@ -1949,25 +1953,15 @@ xlog_dealloc_log(
>  	 */
>  	iclog = log->l_iclog;
>  	for (i = 0; i < log->l_iclog_bufs; i++) {
> -		xfs_buf_lock(iclog->ic_bp);
> -		xfs_buf_unlock(iclog->ic_bp);
> +		down(&iclog->ic_sema);
> +		up(&iclog->ic_sema);
>  		iclog = iclog->ic_next;
>  	}
>  
> -	/*
> -	 * Always need to ensure that the extra buffer does not point to memory
> -	 * owned by another log buffer before we free it. Also, cycle the lock
> -	 * first to ensure we've completed IO on it.
> -	 */
> -	xfs_buf_lock(log->l_xbuf);
> -	xfs_buf_unlock(log->l_xbuf);
> -	xfs_buf_set_empty(log->l_xbuf, BTOBB(log->l_iclog_size));
> -	xfs_buf_free(log->l_xbuf);
> -
>  	iclog = log->l_iclog;
>  	for (i = 0; i < log->l_iclog_bufs; i++) {
> -		xfs_buf_free(iclog->ic_bp);
>  		next_iclog = iclog->ic_next;
> +		kmem_free(iclog->ic_data);
>  		kmem_free(iclog);
>  		iclog = next_iclog;
>  	}
> @@ -2885,8 +2879,6 @@ xlog_state_done_syncing(
>  	ASSERT(iclog->ic_state == XLOG_STATE_SYNCING ||
>  	       iclog->ic_state == XLOG_STATE_IOERROR);
>  	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
> -	ASSERT(iclog->ic_bwritecnt == 1 || iclog->ic_bwritecnt == 2);
> -
>  
>  	/*
>  	 * If we got an error, either on the first buffer, or in the case of
> @@ -2894,13 +2886,8 @@ xlog_state_done_syncing(
>  	 * and none should ever be attempted to be written to disk
>  	 * again.
>  	 */
> -	if (iclog->ic_state != XLOG_STATE_IOERROR) {
> -		if (--iclog->ic_bwritecnt == 1) {
> -			spin_unlock(&log->l_icloglock);
> -			return;
> -		}
> +	if (iclog->ic_state != XLOG_STATE_IOERROR)
>  		iclog->ic_state = XLOG_STATE_DONE_SYNC;
> -	}
>  
>  	/*
>  	 * Someone could be sleeping prior to writing out the next
> diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
> index ac4bca257609..b9c90abb09a2 100644
> --- a/fs/xfs/xfs_log_priv.h
> +++ b/fs/xfs/xfs_log_priv.h
> @@ -178,11 +178,12 @@ typedef struct xlog_ticket {
>   *	the iclog.
>   * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
>   * - ic_next is the pointer to the next iclog in the ring.
> - * - ic_bp is a pointer to the buffer used to write this incore log to disk.
>   * - ic_log is a pointer back to the global log structure.
>   * - ic_callback is a linked list of callback function/argument pairs to be
>   *	called after an iclog finishes writing.
> - * - ic_size is the full size of the header plus data.
> + * - ic_size is the full size of the log buffer, minus the cycle headers.
> + * - ic_io_size is the size of the currently pending log buffer write, which
> + *	might be smaller than ic_size
>   * - ic_offset is the current number of bytes written to in this iclog.
>   * - ic_refcnt is bumped when someone is writing to the log.
>   * - ic_state is the state of the iclog.
> @@ -205,11 +206,10 @@ typedef struct xlog_in_core {
>  	wait_queue_head_t	ic_write_wait;
>  	struct xlog_in_core	*ic_next;
>  	struct xlog_in_core	*ic_prev;
> -	struct xfs_buf		*ic_bp;
>  	struct xlog		*ic_log;
> -	int			ic_size;
> -	int			ic_offset;
> -	int			ic_bwritecnt;
> +	u32			ic_size;
> +	u32			ic_io_size;
> +	u32			ic_offset;
>  	unsigned short		ic_state;
>  	char			*ic_datap;	/* pointer to iclog data */
>  
> @@ -225,6 +225,10 @@ typedef struct xlog_in_core {
>  #ifdef DEBUG
>  	bool			ic_fail_crc : 1;
>  #endif
> +	struct semaphore	ic_sema;
> +	struct work_struct	ic_end_io_work;
> +	struct bio		ic_bio;
> +	struct bio_vec		ic_bvec[];
>  } xlog_in_core_t;
>  
>  /*
> @@ -352,8 +356,6 @@ struct xlog {
>  	struct xfs_mount	*l_mp;	        /* mount point */
>  	struct xfs_ail		*l_ailp;	/* AIL log is working with */
>  	struct xfs_cil		*l_cilp;	/* CIL log is working with */
> -	struct xfs_buf		*l_xbuf;        /* extra buffer for log
> -						 * wrapping */
>  	struct xfs_buftarg	*l_targ;        /* buftarg of log */
>  	struct delayed_work	l_work;		/* background flush work */
>  	uint			l_flags;
> -- 
> 2.20.1
> 

Re: [PATCH 16/24] xfs: use bios directly to write log buffers

[Christoph Hellwig]

On Mon, Jun 17, 2019 at 04:27:51PM -0700, Darrick J. Wong wrote:
> Ugh, I don't really like this awkwardly split else/#endif construction
> here.  Can we simply do:
> 
> error = blk_status_to_errno(iclog->ic_bio.bi_status);
> 
> #ifdef DEBUG
> if (iclog->ic_fail_crc)
> 	error = -EIO;
> #endif
> 
> instead?

Fine with me.

[PATCH 17/24] xfs: move the log ioend workqueue to struct xlog

[Christoph Hellwig]

Move the workqueue used for log I/O completions from struct xfs_mount
to struct xlog to keep it self contained in the log code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c      | 13 +++++++++++--
 fs/xfs/xfs_log_priv.h |  1 +
 fs/xfs/xfs_mount.h    |  1 -
 fs/xfs/xfs_super.c    | 11 +----------
 4 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 0a8a43d77385..66b87cce69b9 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1490,11 +1490,19 @@ xlog_alloc_log(
 	*iclogp = log->l_iclog;			/* complete ring */
 	log->l_iclog->ic_prev = prev_iclog;	/* re-write 1st prev ptr */
 
+	log->l_ioend_workqueue = alloc_workqueue("xfs-log/%s",
+			WQ_MEM_RECLAIM | WQ_FREEZABLE | WQ_HIGHPRI, 0,
+			mp->m_fsname);
+	if (!log->l_ioend_workqueue)
+		goto out_free_iclog;
+
 	error = xlog_cil_init(log);
 	if (error)
-		goto out_free_iclog;
+		goto out_destroy_workqueue;
 	return log;
 
+out_destroy_workqueue:
+	destroy_workqueue(log->l_ioend_workqueue);
 out_free_iclog:
 	for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
 		prev_iclog = iclog->ic_next;
@@ -1691,7 +1699,7 @@ xlog_bio_end_io(
 {
 	struct xlog_in_core	*iclog = bio->bi_private;
 
-	queue_work(iclog->ic_log->l_mp->m_log_workqueue,
+	queue_work(iclog->ic_log->l_ioend_workqueue,
 		   &iclog->ic_end_io_work);
 }
 
@@ -1946,6 +1954,7 @@ xlog_dealloc_log(
 	int		i;
 
 	xlog_cil_destroy(log);
+	destroy_workqueue(log->l_ioend_workqueue);
 
 	/*
 	 * Cycle all the iclogbuf locks to make sure all log IO completion
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index b9c90abb09a2..a20f5e919a26 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -357,6 +357,7 @@ struct xlog {
 	struct xfs_ail		*l_ailp;	/* AIL log is working with */
 	struct xfs_cil		*l_cilp;	/* CIL log is working with */
 	struct xfs_buftarg	*l_targ;        /* buftarg of log */
+	struct workqueue_struct	*l_ioend_workqueue; /* for I/O completions */
 	struct delayed_work	l_work;		/* background flush work */
 	uint			l_flags;
 	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index c81a5cd7c228..8d188155dca3 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -198,7 +198,6 @@ typedef struct xfs_mount {
 	struct workqueue_struct	*m_unwritten_workqueue;
 	struct workqueue_struct	*m_cil_workqueue;
 	struct workqueue_struct	*m_reclaim_workqueue;
-	struct workqueue_struct	*m_log_workqueue;
 	struct workqueue_struct *m_eofblocks_workqueue;
 	struct workqueue_struct	*m_sync_workqueue;
 
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index a14d11d78bd8..7cb0d2a01c41 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -840,16 +840,10 @@ xfs_init_mount_workqueues(
 	if (!mp->m_reclaim_workqueue)
 		goto out_destroy_cil;
 
-	mp->m_log_workqueue = alloc_workqueue("xfs-log/%s",
-			WQ_MEM_RECLAIM|WQ_FREEZABLE|WQ_HIGHPRI, 0,
-			mp->m_fsname);
-	if (!mp->m_log_workqueue)
-		goto out_destroy_reclaim;
-
 	mp->m_eofblocks_workqueue = alloc_workqueue("xfs-eofblocks/%s",
 			WQ_MEM_RECLAIM|WQ_FREEZABLE, 0, mp->m_fsname);
 	if (!mp->m_eofblocks_workqueue)
-		goto out_destroy_log;
+		goto out_destroy_reclaim;
 
 	mp->m_sync_workqueue = alloc_workqueue("xfs-sync/%s", WQ_FREEZABLE, 0,
 					       mp->m_fsname);
@@ -860,8 +854,6 @@ xfs_init_mount_workqueues(
 
 out_destroy_eofb:
 	destroy_workqueue(mp->m_eofblocks_workqueue);
-out_destroy_log:
-	destroy_workqueue(mp->m_log_workqueue);
 out_destroy_reclaim:
 	destroy_workqueue(mp->m_reclaim_workqueue);
 out_destroy_cil:
@@ -880,7 +872,6 @@ xfs_destroy_mount_workqueues(
 {
 	destroy_workqueue(mp->m_sync_workqueue);
 	destroy_workqueue(mp->m_eofblocks_workqueue);
-	destroy_workqueue(mp->m_log_workqueue);
 	destroy_workqueue(mp->m_reclaim_workqueue);
 	destroy_workqueue(mp->m_cil_workqueue);
 	destroy_workqueue(mp->m_unwritten_workqueue);
-- 
2.20.1

[PATCH 18/24] xfs: return an offset instead of a pointer from xlog_align

[Christoph Hellwig]

This simplifies both the helper and the callers.  We lost a bit of
size sanity checking, but that is already covered by KASAN if needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log_recover.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 4139b907e9cd..74fd3784bcb7 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -151,20 +151,14 @@ xlog_put_bp(
  * Return the address of the start of the given block number's data
  * in a log buffer.  The buffer covers a log sector-aligned region.
  */
-STATIC char *
+static inline unsigned int
 xlog_align(
 	struct xlog	*log,
-	xfs_daddr_t	blk_no,
-	int		nbblks,
-	struct xfs_buf	*bp)
+	xfs_daddr_t	blk_no)
 {
-	xfs_daddr_t	offset = blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1);
-
-	ASSERT(offset + nbblks <= bp->b_length);
-	return bp->b_addr + BBTOB(offset);
+	return BBTOB(blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1));
 }
 
-
 /*
  * nbblks should be uint, but oh well.  Just want to catch that 32-bit length.
  */
@@ -216,7 +210,7 @@ xlog_bread(
 	if (error)
 		return error;
 
-	*offset = xlog_align(log, blk_no, nbblks, bp);
+	*offset = bp->b_addr + xlog_align(log, blk_no);
 	return 0;
 }
 
@@ -1713,7 +1707,7 @@ xlog_write_log_records(
 
 		}
 
-		offset = xlog_align(log, start_block, endcount, bp);
+		offset = bp->b_addr + xlog_align(log, start_block);
 		for (; j < endcount; j++) {
 			xlog_add_record(log, offset, cycle, i+j,
 					tail_cycle, tail_block);
-- 
2.20.1

[PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Christoph Hellwig]

The xfs_buf structure is basically used as a glorified container for
a memory allocation in the log recovery code.  Replace it with a
call to kmem_alloc_large and a simple abstraction to read into or
write from it synchronously using chained bios.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/Makefile          |   1 +
 fs/xfs/xfs_bio_io.c      |  61 ++++++++++
 fs/xfs/xfs_linux.h       |   3 +
 fs/xfs/xfs_log_recover.c | 241 ++++++++++++++-------------------------
 4 files changed, 149 insertions(+), 157 deletions(-)
 create mode 100644 fs/xfs/xfs_bio_io.c

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 91831975363b..701028e3e4ac 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -62,6 +62,7 @@ xfs-y				+= xfs_aops.o \
 				   xfs_attr_inactive.o \
 				   xfs_attr_list.o \
 				   xfs_bmap_util.o \
+				   xfs_bio_io.o \
 				   xfs_buf.o \
 				   xfs_dir2_readdir.o \
 				   xfs_discard.o \
diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
new file mode 100644
index 000000000000..757c1d9293eb
--- /dev/null
+++ b/fs/xfs/xfs_bio_io.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Christoph Hellwig.
+ */
+#include "xfs.h"
+
+static inline unsigned int bio_max_vecs(unsigned int count)
+{
+	return min_t(unsigned, howmany(count, PAGE_SIZE), BIO_MAX_PAGES);
+}
+
+int
+xfs_rw_bdev(
+	struct block_device	*bdev,
+	sector_t		sector,
+	unsigned int		count,
+	char			*data,
+	unsigned int		op)
+
+{
+	unsigned int		is_vmalloc = is_vmalloc_addr(data);
+	unsigned int		left = count;
+	int			error;
+	struct bio		*bio;
+
+	if (is_vmalloc && op == REQ_OP_WRITE)
+		flush_kernel_vmap_range(data, count);
+
+	bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
+	bio_set_dev(bio, bdev);
+	bio->bi_iter.bi_sector = sector;
+	bio->bi_opf = op | REQ_META | REQ_SYNC;
+
+	do {
+		struct page	*page = kmem_to_page(data);
+		unsigned int	off = offset_in_page(data);
+		unsigned int	len = min_t(unsigned, left, PAGE_SIZE - off);
+
+		while (bio_add_page(bio, page, len, off) != len) {
+			struct bio	*prev = bio;
+
+			bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
+			bio_copy_dev(bio, prev);
+			bio->bi_iter.bi_sector = bio_end_sector(prev);
+			bio->bi_opf = prev->bi_opf;
+			bio_chain(bio, prev);
+
+			submit_bio(prev);
+		}
+
+		data += len;
+		left -= len;
+	} while (left > 0);
+
+	error = submit_bio_wait(bio);
+	bio_put(bio);
+
+	if (is_vmalloc && op == REQ_OP_READ)
+		invalidate_kernel_vmap_range(data, count);
+	return error;
+}
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index b78287666309..ca15105681ca 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -219,6 +219,9 @@ static inline uint64_t howmany_64(uint64_t x, uint32_t y)
 	return x;
 }
 
+int xfs_rw_bdev(struct block_device *bdev, sector_t sector, unsigned int count,
+		char *data, unsigned int op);
+
 #define ASSERT_ALWAYS(expr)	\
 	(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
 
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 74fd3784bcb7..a28c9dc8f1f2 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -92,17 +92,14 @@ xlog_verify_bp(
 }
 
 /*
- * Allocate a buffer to hold log data.  The buffer needs to be able
- * to map to a range of nbblks basic blocks at any valid (basic
- * block) offset within the log.
+ * Allocate a buffer to hold log data.  The buffer needs to be able to map to
+ * a range of nbblks basic blocks at any valid offset within the log.
  */
-STATIC xfs_buf_t *
+static char *
 xlog_get_bp(
 	struct xlog	*log,
 	int		nbblks)
 {
-	struct xfs_buf	*bp;
-
 	/*
 	 * Pass log block 0 since we don't have an addr yet, buffer will be
 	 * verified on read.
@@ -115,36 +112,23 @@ xlog_get_bp(
 	}
 
 	/*
-	 * We do log I/O in units of log sectors (a power-of-2
-	 * multiple of the basic block size), so we round up the
-	 * requested size to accommodate the basic blocks required
-	 * for complete log sectors.
+	 * We do log I/O in units of log sectors (a power-of-2 multiple of the
+	 * basic block size), so we round up the requested size to accommodate
+	 * the basic blocks required for complete log sectors.
 	 *
-	 * In addition, the buffer may be used for a non-sector-
-	 * aligned block offset, in which case an I/O of the
-	 * requested size could extend beyond the end of the
-	 * buffer.  If the requested size is only 1 basic block it
-	 * will never straddle a sector boundary, so this won't be
-	 * an issue.  Nor will this be a problem if the log I/O is
-	 * done in basic blocks (sector size 1).  But otherwise we
-	 * extend the buffer by one extra log sector to ensure
-	 * there's space to accommodate this possibility.
+	 * In addition, the buffer may be used for a non-sector-aligned block
+	 * offset, in which case an I/O of the requested size could extend
+	 * beyond the end of the buffer.  If the requested size is only 1 basic
+	 * block it will never straddle a sector boundary, so this won't be an
+	 * issue.  Nor will this be a problem if the log I/O is done in basic
+	 * blocks (sector size 1).  But otherwise we extend the buffer by one
+	 * extra log sector to ensure there's space to accommodate this
+	 * possibility.
 	 */
 	if (nbblks > 1 && log->l_sectBBsize > 1)
 		nbblks += log->l_sectBBsize;
 	nbblks = round_up(nbblks, log->l_sectBBsize);
-
-	bp = xfs_buf_get_uncached(log->l_targ, nbblks, 0);
-	if (bp)
-		xfs_buf_unlock(bp);
-	return bp;
-}
-
-STATIC void
-xlog_put_bp(
-	xfs_buf_t	*bp)
-{
-	xfs_buf_free(bp);
+	return kmem_alloc_large(BBTOB(nbblks), KM_MAYFAIL);
 }
 
 /*
@@ -159,17 +143,15 @@ xlog_align(
 	return BBTOB(blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1));
 }
 
-/*
- * nbblks should be uint, but oh well.  Just want to catch that 32-bit length.
- */
-STATIC int
-xlog_bread_noalign(
-	struct xlog	*log,
-	xfs_daddr_t	blk_no,
-	int		nbblks,
-	struct xfs_buf	*bp)
+static int
+xlog_do_io(
+	struct xlog		*log,
+	xfs_daddr_t		blk_no,
+	unsigned int		nbblks,
+	char			*data,
+	unsigned int		op)
 {
-	int		error;
+	int			error;
 
 	if (!xlog_verify_bp(log, blk_no, nbblks)) {
 		xfs_warn(log->l_mp,
@@ -181,107 +163,53 @@ xlog_bread_noalign(
 
 	blk_no = round_down(blk_no, log->l_sectBBsize);
 	nbblks = round_up(nbblks, log->l_sectBBsize);
-
 	ASSERT(nbblks > 0);
-	ASSERT(nbblks <= bp->b_length);
-
-	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
-	bp->b_flags |= XBF_READ;
-	bp->b_io_length = nbblks;
-	bp->b_error = 0;
 
-	error = xfs_buf_submit(bp);
-	if (error && !XFS_FORCED_SHUTDOWN(log->l_mp))
-		xfs_buf_ioerror_alert(bp, __func__);
+	error = xfs_rw_bdev(log->l_targ->bt_bdev, log->l_logBBstart + blk_no,
+			BBTOB(nbblks), data, op);
+	if (error && !XFS_FORCED_SHUTDOWN(log->l_mp)) {
+		xfs_alert(log->l_mp,
+			  "log recovery %s I/O error at daddr 0x%llx len %d error %d",
+			  op == REQ_OP_WRITE ? "write" : "read",
+			  blk_no, nbblks, error);
+	}
 	return error;
 }
 
 STATIC int
-xlog_bread(
+xlog_bread_noalign(
 	struct xlog	*log,
 	xfs_daddr_t	blk_no,
 	int		nbblks,
-	struct xfs_buf	*bp,
-	char		**offset)
+	char		*data)
 {
-	int		error;
-
-	error = xlog_bread_noalign(log, blk_no, nbblks, bp);
-	if (error)
-		return error;
-
-	*offset = bp->b_addr + xlog_align(log, blk_no);
-	return 0;
+	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
 }
 
-/*
- * Read at an offset into the buffer. Returns with the buffer in it's original
- * state regardless of the result of the read.
- */
 STATIC int
-xlog_bread_offset(
+xlog_bread(
 	struct xlog	*log,
-	xfs_daddr_t	blk_no,		/* block to read from */
-	int		nbblks,		/* blocks to read */
-	struct xfs_buf	*bp,
-	char		*offset)
+	xfs_daddr_t	blk_no,
+	int		nbblks,
+	char		*data,
+	char		**offset)
 {
-	char		*orig_offset = bp->b_addr;
-	int		orig_len = BBTOB(bp->b_length);
-	int		error, error2;
-
-	error = xfs_buf_associate_memory(bp, offset, BBTOB(nbblks));
-	if (error)
-		return error;
-
-	error = xlog_bread_noalign(log, blk_no, nbblks, bp);
+	int		error;
 
-	/* must reset buffer pointer even on error */
-	error2 = xfs_buf_associate_memory(bp, orig_offset, orig_len);
-	if (error)
-		return error;
-	return error2;
+	error = xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
+	if (!error)
+		*offset = data + xlog_align(log, blk_no);
+	return error;
 }
 
-/*
- * Write out the buffer at the given block for the given number of blocks.
- * The buffer is kept locked across the write and is returned locked.
- * This can only be used for synchronous log writes.
- */
 STATIC int
 xlog_bwrite(
 	struct xlog	*log,
 	xfs_daddr_t	blk_no,
 	int		nbblks,
-	struct xfs_buf	*bp)
+	char		*data)
 {
-	int		error;
-
-	if (!xlog_verify_bp(log, blk_no, nbblks)) {
-		xfs_warn(log->l_mp,
-			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
-			 blk_no, nbblks);
-		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_HIGH, log->l_mp);
-		return -EFSCORRUPTED;
-	}
-
-	blk_no = round_down(blk_no, log->l_sectBBsize);
-	nbblks = round_up(nbblks, log->l_sectBBsize);
-
-	ASSERT(nbblks > 0);
-	ASSERT(nbblks <= bp->b_length);
-
-	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
-	xfs_buf_hold(bp);
-	xfs_buf_lock(bp);
-	bp->b_io_length = nbblks;
-	bp->b_error = 0;
-
-	error = xfs_bwrite(bp);
-	if (error)
-		xfs_buf_ioerror_alert(bp, __func__);
-	xfs_buf_relse(bp);
-	return error;
+	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_WRITE);
 }
 
 #ifdef DEBUG
@@ -399,7 +327,7 @@ xlog_recover_iodone(
 STATIC int
 xlog_find_cycle_start(
 	struct xlog	*log,
-	struct xfs_buf	*bp,
+	char		*bp,
 	xfs_daddr_t	first_blk,
 	xfs_daddr_t	*last_blk,
 	uint		cycle)
@@ -449,7 +377,7 @@ xlog_find_verify_cycle(
 {
 	xfs_daddr_t	i, j;
 	uint		cycle;
-	xfs_buf_t	*bp;
+	char		*bp;
 	xfs_daddr_t	bufblks;
 	char		*buf = NULL;
 	int		error = 0;
@@ -492,7 +420,7 @@ xlog_find_verify_cycle(
 	*new_blk = -1;
 
 out:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	return error;
 }
 
@@ -516,7 +444,7 @@ xlog_find_verify_log_record(
 	int			extra_bblks)
 {
 	xfs_daddr_t		i;
-	xfs_buf_t		*bp;
+	char			*bp;
 	char			*offset = NULL;
 	xlog_rec_header_t	*head = NULL;
 	int			error = 0;
@@ -601,7 +529,7 @@ xlog_find_verify_log_record(
 		*last_blk = i;
 
 out:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	return error;
 }
 
@@ -623,7 +551,7 @@ xlog_find_head(
 	struct xlog	*log,
 	xfs_daddr_t	*return_head_blk)
 {
-	xfs_buf_t	*bp;
+	char		*bp;
 	char		*offset;
 	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
 	int		num_scan_bblks;
@@ -854,7 +782,7 @@ xlog_find_head(
 			goto bp_err;
 	}
 
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	if (head_blk == log_bbnum)
 		*return_head_blk = 0;
 	else
@@ -868,7 +796,7 @@ xlog_find_head(
 	return 0;
 
  bp_err:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 
 	if (error)
 		xfs_warn(log->l_mp, "failed to find log head");
@@ -889,7 +817,7 @@ xlog_rseek_logrec_hdr(
 	xfs_daddr_t		head_blk,
 	xfs_daddr_t		tail_blk,
 	int			count,
-	struct xfs_buf		*bp,
+	char			*bp,
 	xfs_daddr_t		*rblk,
 	struct xlog_rec_header	**rhead,
 	bool			*wrapped)
@@ -963,7 +891,7 @@ xlog_seek_logrec_hdr(
 	xfs_daddr_t		head_blk,
 	xfs_daddr_t		tail_blk,
 	int			count,
-	struct xfs_buf		*bp,
+	char			*bp,
 	xfs_daddr_t		*rblk,
 	struct xlog_rec_header	**rhead,
 	bool			*wrapped)
@@ -1063,7 +991,7 @@ xlog_verify_tail(
 	int			hsize)
 {
 	struct xlog_rec_header	*thead;
-	struct xfs_buf		*bp;
+	char			*bp;
 	xfs_daddr_t		first_bad;
 	int			error = 0;
 	bool			wrapped;
@@ -1123,7 +1051,7 @@ xlog_verify_tail(
 		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
 			 orig_tail, *tail_blk);
 out:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	return error;
 }
 
@@ -1145,13 +1073,13 @@ xlog_verify_head(
 	struct xlog		*log,
 	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
 	xfs_daddr_t		*tail_blk,	/* out: tail block */
-	struct xfs_buf		*bp,
+	char			*bp,
 	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
 	struct xlog_rec_header	**rhead,	/* ptr to last record */
 	bool			*wrapped)	/* last rec. wraps phys. log */
 {
 	struct xlog_rec_header	*tmp_rhead;
-	struct xfs_buf		*tmp_bp;
+	char			*tmp_bp;
 	xfs_daddr_t		first_bad;
 	xfs_daddr_t		tmp_rhead_blk;
 	int			found;
@@ -1170,7 +1098,7 @@ xlog_verify_head(
 	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
 				      XLOG_MAX_ICLOGS, tmp_bp, &tmp_rhead_blk,
 				      &tmp_rhead, &tmp_wrapped);
-	xlog_put_bp(tmp_bp);
+	kmem_free(tmp_bp);
 	if (error < 0)
 		return error;
 
@@ -1260,7 +1188,7 @@ xlog_check_unmount_rec(
 	xfs_daddr_t		*tail_blk,
 	struct xlog_rec_header	*rhead,
 	xfs_daddr_t		rhead_blk,
-	struct xfs_buf		*bp,
+	char			*bp,
 	bool			*clean)
 {
 	struct xlog_op_header	*op_head;
@@ -1382,7 +1310,7 @@ xlog_find_tail(
 {
 	xlog_rec_header_t	*rhead;
 	char			*offset = NULL;
-	xfs_buf_t		*bp;
+	char			*bp;
 	int			error;
 	xfs_daddr_t		rhead_blk;
 	xfs_lsn_t		tail_lsn;
@@ -1503,7 +1431,7 @@ xlog_find_tail(
 		error = xlog_clear_stale_blocks(log, tail_lsn);
 
 done:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 
 	if (error)
 		xfs_warn(log->l_mp, "failed to locate log tail");
@@ -1531,7 +1459,7 @@ xlog_find_zeroed(
 	struct xlog	*log,
 	xfs_daddr_t	*blk_no)
 {
-	xfs_buf_t	*bp;
+	char		*bp;
 	char		*offset;
 	uint	        first_cycle, last_cycle;
 	xfs_daddr_t	new_blk, last_blk, start_blk;
@@ -1551,7 +1479,7 @@ xlog_find_zeroed(
 	first_cycle = xlog_get_cycle(offset);
 	if (first_cycle == 0) {		/* completely zeroed log */
 		*blk_no = 0;
-		xlog_put_bp(bp);
+		kmem_free(bp);
 		return 1;
 	}
 
@@ -1562,7 +1490,7 @@ xlog_find_zeroed(
 
 	last_cycle = xlog_get_cycle(offset);
 	if (last_cycle != 0) {		/* log completely written to */
-		xlog_put_bp(bp);
+		kmem_free(bp);
 		return 0;
 	}
 
@@ -1608,7 +1536,7 @@ xlog_find_zeroed(
 
 	*blk_no = last_blk;
 bp_err:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	if (error)
 		return error;
 	return 1;
@@ -1651,7 +1579,7 @@ xlog_write_log_records(
 	int		tail_block)
 {
 	char		*offset;
-	xfs_buf_t	*bp;
+	char		*bp;
 	int		balign, ealign;
 	int		sectbb = log->l_sectBBsize;
 	int		end_block = start_block + blocks;
@@ -1699,15 +1627,14 @@ xlog_write_log_records(
 		 */
 		ealign = round_down(end_block, sectbb);
 		if (j == 0 && (start_block + endcount > ealign)) {
-			offset = bp->b_addr + BBTOB(ealign - start_block);
-			error = xlog_bread_offset(log, ealign, sectbb,
-							bp, offset);
+			error = xlog_bread_noalign(log, ealign, sectbb,
+					bp + BBTOB(ealign - start_block));
 			if (error)
 				break;
 
 		}
 
-		offset = bp->b_addr + xlog_align(log, start_block);
+		offset = bp + xlog_align(log, start_block);
 		for (; j < endcount; j++) {
 			xlog_add_record(log, offset, cycle, i+j,
 					tail_cycle, tail_block);
@@ -1721,7 +1648,7 @@ xlog_write_log_records(
 	}
 
  out_put_bp:
-	xlog_put_bp(bp);
+	kmem_free(bp);
 	return error;
 }
 
@@ -5301,7 +5228,7 @@ xlog_do_recovery_pass(
 	xfs_daddr_t		blk_no, rblk_no;
 	xfs_daddr_t		rhead_blk;
 	char			*offset;
-	xfs_buf_t		*hbp, *dbp;
+	char			*hbp, *dbp;
 	int			error = 0, h_size, h_len;
 	int			error2 = 0;
 	int			bblks, split_bblks;
@@ -5368,7 +5295,7 @@ xlog_do_recovery_pass(
 			hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
 			if (h_size % XLOG_HEADER_CYCLE_SIZE)
 				hblks++;
-			xlog_put_bp(hbp);
+			kmem_free(hbp);
 			hbp = xlog_get_bp(log, hblks);
 		} else {
 			hblks = 1;
@@ -5384,7 +5311,7 @@ xlog_do_recovery_pass(
 		return -ENOMEM;
 	dbp = xlog_get_bp(log, BTOBB(h_size));
 	if (!dbp) {
-		xlog_put_bp(hbp);
+		kmem_free(hbp);
 		return -ENOMEM;
 	}
 
@@ -5399,7 +5326,7 @@ xlog_do_recovery_pass(
 			/*
 			 * Check for header wrapping around physical end-of-log
 			 */
-			offset = hbp->b_addr;
+			offset = hbp;
 			split_hblks = 0;
 			wrapped_hblks = 0;
 			if (blk_no + hblks <= log->l_logBBsize) {
@@ -5435,8 +5362,8 @@ xlog_do_recovery_pass(
 				 *   - order is important.
 				 */
 				wrapped_hblks = hblks - split_hblks;
-				error = xlog_bread_offset(log, 0,
-						wrapped_hblks, hbp,
+				error = xlog_bread_noalign(log, 0,
+						wrapped_hblks,
 						offset + BBTOB(split_hblks));
 				if (error)
 					goto bread_err2;
@@ -5467,7 +5394,7 @@ xlog_do_recovery_pass(
 			} else {
 				/* This log record is split across the
 				 * physical end of log */
-				offset = dbp->b_addr;
+				offset = dbp;
 				split_bblks = 0;
 				if (blk_no != log->l_logBBsize) {
 					/* some data is before the physical
@@ -5496,8 +5423,8 @@ xlog_do_recovery_pass(
 				 *   _first_, then the log start (LR header end)
 				 *   - order is important.
 				 */
-				error = xlog_bread_offset(log, 0,
-						bblks - split_bblks, dbp,
+				error = xlog_bread_noalign(log, 0,
+						bblks - split_bblks,
 						offset + BBTOB(split_bblks));
 				if (error)
 					goto bread_err2;
@@ -5545,9 +5472,9 @@ xlog_do_recovery_pass(
 	}
 
  bread_err2:
-	xlog_put_bp(dbp);
+	kmem_free(dbp);
  bread_err1:
-	xlog_put_bp(hbp);
+	kmem_free(hbp);
 
 	/*
 	 * Submit buffers that have been added from the last record processed,
-- 
2.20.1

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Dave Chinner]

On Wed, Jun 05, 2019 at 09:15:06PM +0200, Christoph Hellwig wrote:
> The xfs_buf structure is basically used as a glorified container for
> a memory allocation in the log recovery code.  Replace it with a
> call to kmem_alloc_large and a simple abstraction to read into or
> write from it synchronously using chained bios.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I've bisected a generic/006 failure w/ 5.2 + linux-xfs/for-next down
to this patch. The failure takes several forms:

	a) slab page list corruption and endless console spew
	b) failure to verify log record headers finding the header
	  and asserting:

[  607.977165] XFS (sdf): Mounting V5 Filesystem
[  608.014844] XFS (sdf): Log inconsistent (didn't find previous header)
[  608.016296] XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 471

	c) record corruption being found when trying to verify
	headers.

It's a completely repeatable failure, running on iscsi block device
with a 4k sector size. Change the sector size to 512 bytes, the
issue _appears_ to go away, probably because the different log
sector sizes result in different IO sizes and shapes and so avoid
the issue I think is occuring....

> diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
> new file mode 100644
> index 000000000000..757c1d9293eb
> --- /dev/null
> +++ b/fs/xfs/xfs_bio_io.c
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019 Christoph Hellwig.
> + */
> +#include "xfs.h"
> +
> +static inline unsigned int bio_max_vecs(unsigned int count)
> +{
> +	return min_t(unsigned, howmany(count, PAGE_SIZE), BIO_MAX_PAGES);
> +}
> +
> +int
> +xfs_rw_bdev(
> +	struct block_device	*bdev,
> +	sector_t		sector,
> +	unsigned int		count,
> +	char			*data,
> +	unsigned int		op)
> +
> +{
> +	unsigned int		is_vmalloc = is_vmalloc_addr(data);
> +	unsigned int		left = count;
> +	int			error;
> +	struct bio		*bio;
> +
> +	if (is_vmalloc && op == REQ_OP_WRITE)
> +		flush_kernel_vmap_range(data, count);
> +
> +	bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
> +	bio_set_dev(bio, bdev);
> +	bio->bi_iter.bi_sector = sector;
> +	bio->bi_opf = op | REQ_META | REQ_SYNC;
> +
> +	do {
> +		struct page	*page = kmem_to_page(data);
> +		unsigned int	off = offset_in_page(data);
> +		unsigned int	len = min_t(unsigned, left, PAGE_SIZE - off);
> +
> +		while (bio_add_page(bio, page, len, off) != len) {
> +			struct bio	*prev = bio;
> +
> +			bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
> +			bio_copy_dev(bio, prev);
> +			bio->bi_iter.bi_sector = bio_end_sector(prev);
> +			bio->bi_opf = prev->bi_opf;
> +			bio_chain(bio, prev);
> +
> +			submit_bio(prev);
> +		}

I suspect the problem is here. This chains bios in a different order
to xfs_chain_bio() in the data writeback path, and it looks to be
mis-behaving.

The tracing I have shows this interesting case right before we hit
the bad state:

    53.622521: bprint:               xlog_find_zeroed: first_cycle 0x1
    53.623277: bprint:               xlog_find_zeroed: last_cycle 0x0
    53.633060: bprint:               xlog_find_zeroed: start_blk 0xf0, last_blk 0x10f0
    53.633320: bprint:               xlog_find_verify_cycle: bufblks 0x2000

And the I/O that is now issued by xlog_find_verify_cycle() is:

    53.633321: bprint:               xfs_rw_bdev: s 0xa00140, c 0x200000, op 0

for 2MB of log space to see if there's any holes in the iclog range
prior to the last cycle change. THis is issued as two bios:

    53.633340: bprint:               xfs_rw_bdev: sb prev s 0xa00140 0xa00d10
    53.633340: block_bio_queue:      8,80 RSM 10486080 + 3024 [mount]

The first is 3024 sectors in length

    53.633350: block_split:          8,80 RSM 10486080 / 10488640 [mount]

which we chain to our next bio and submit it. It is then split
and chained in the block layer

    53.633352: block_getrq:          8,80 RSM 10486080 + 2560 [mount]
    53.633353: block_rq_insert:      8,80 RSM 1310720 () 10486080 + 2560 [mount]
    53.633362: block_rq_issue:       8,80 RSM 1310720 () 10486080 + 2560 [kworker/3:1H]
    53.633418: block_getrq:          8,80 RSM 10488640 + 464 [mount]
    53.633420: block_rq_insert:      8,80 RSM 237568 () 10488640 + 464 [mount]
    53.633426: block_rq_issue:       8,80 RSM 237568 () 10488640 + 464 [kworker/3:1H]

and both bios are issued, and then:

> +
> +		data += len;
> +		left -= len;
> +	} while (left > 0);
> +
> +	error = submit_bio_wait(bio);
> +	bio_put(bio);

    53.633465: bprint:               xfs_rw_bdev: sbw s 0xa00d10 0xa01140
    53.633466: block_bio_queue:      8,80 RSM 10489104 + 1072 [mount]

we submit our second bio and wait on it to complete.

    53.633471: block_getrq:          8,80 RSM 10489104 + 1072 [mount]
    53.633472: block_rq_insert:      8,80 RSM 548864 () 10489104 + 1072 [mount]
    53.633478: block_rq_issue:       8,80 RSM 548864 () 10489104 + 1072 [kworker/3:1H]
    53.636267: block_rq_complete:    8,80 RSM () 10488640 + 464 [0]
    53.640807: block_rq_complete:    8,80 RSM () 10489104 + 1072 [0]

So at this point the smaller split bio has completed, as has the second
bio we called submit_bio_wait() on, but the next trace:

    53.640987: bprint:               xlog_find_zeroed: new_blk 0x10c, last_blk 0x10c

Indicates that submit_bio_wait has completed. The first part of the
split bio hasn't completed yet, so we have undefined contents in the
buffer and it finds a zero cycle in the range we were searching. So,
we call into xlog_find_verify_log_record() which issues new IO at
the start of the range:

    53.640990: bprint:               xfs_rw_bdev: s 0xa00140, c 0x4000, op 0
    53.640992: bprint:               xfs_rw_bdev: sbw s 0xa00140 0xa00160
    53.640993: block_bio_queue:      8,80 RSM 10486080 + 32 [mount]
    53.640997: block_getrq:          8,80 RSM 10486080 + 32 [mount]
    53.640998: block_rq_insert:      8,80 RSM 16384 () 10486080 + 32 [mount]
    53.641010: block_rq_issue:       8,80 RSM 16384 () 10486080 + 32 [kworker/3:1H]

And then we see this happen:

    53.651936: block_rq_complete:    8,80 RSM () 10486080 + 2560 [0]
    53.652033: block_rq_complete:    8,80 RSM () 10486080 + 32 [0]

There's two completions for overlapping IOs, and one of them is the
remaining bio that was split in the block layer. And because when we
actually read that record, we don't find a cycle number change in it
or even a complete log record, we get this:

    53.652058: console:              [   53.491104] XFS (sdf): Log inconsistent (didn't find previous header)
    53.653500: console:              [   53.492547] XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 474

The assert fires.

It looks like blk_split_request() has corrupted out bio chain by
splitting a bio in the chain and not linking it back together
correctly.

It's not exactly clear to me how nested bio chaining like this is
supposed to work, but it looks to me like it is the source of the
log recovery corruption I'm seeing here...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Darrick J. Wong]

On Mon, Jul 08, 2019 at 05:37:40PM +1000, Dave Chinner wrote:
> On Wed, Jun 05, 2019 at 09:15:06PM +0200, Christoph Hellwig wrote:
> > The xfs_buf structure is basically used as a glorified container for
> > a memory allocation in the log recovery code.  Replace it with a
> > call to kmem_alloc_large and a simple abstraction to read into or
> > write from it synchronously using chained bios.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> I've bisected a generic/006 failure w/ 5.2 + linux-xfs/for-next down
> to this patch. The failure takes several forms:
> 
> 	a) slab page list corruption and endless console spew
> 	b) failure to verify log record headers finding the header
> 	  and asserting:
> 
> [  607.977165] XFS (sdf): Mounting V5 Filesystem
> [  608.014844] XFS (sdf): Log inconsistent (didn't find previous header)
> [  608.016296] XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 471
> 
> 	c) record corruption being found when trying to verify
> 	headers.
> 
> It's a completely repeatable failure, running on iscsi block device
> with a 4k sector size. Change the sector size to 512 bytes, the
> issue _appears_ to go away, probably because the different log
> sector sizes result in different IO sizes and shapes and so avoid
> the issue I think is occuring....
> 
> > diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
> > new file mode 100644
> > index 000000000000..757c1d9293eb
> > --- /dev/null
> > +++ b/fs/xfs/xfs_bio_io.c
> > @@ -0,0 +1,61 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2019 Christoph Hellwig.
> > + */
> > +#include "xfs.h"
> > +
> > +static inline unsigned int bio_max_vecs(unsigned int count)
> > +{
> > +	return min_t(unsigned, howmany(count, PAGE_SIZE), BIO_MAX_PAGES);
> > +}
> > +
> > +int
> > +xfs_rw_bdev(
> > +	struct block_device	*bdev,
> > +	sector_t		sector,
> > +	unsigned int		count,
> > +	char			*data,
> > +	unsigned int		op)
> > +
> > +{
> > +	unsigned int		is_vmalloc = is_vmalloc_addr(data);
> > +	unsigned int		left = count;
> > +	int			error;
> > +	struct bio		*bio;
> > +
> > +	if (is_vmalloc && op == REQ_OP_WRITE)
> > +		flush_kernel_vmap_range(data, count);
> > +
> > +	bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
> > +	bio_set_dev(bio, bdev);
> > +	bio->bi_iter.bi_sector = sector;
> > +	bio->bi_opf = op | REQ_META | REQ_SYNC;
> > +
> > +	do {
> > +		struct page	*page = kmem_to_page(data);
> > +		unsigned int	off = offset_in_page(data);
> > +		unsigned int	len = min_t(unsigned, left, PAGE_SIZE - off);
> > +
> > +		while (bio_add_page(bio, page, len, off) != len) {
> > +			struct bio	*prev = bio;
> > +
> > +			bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
> > +			bio_copy_dev(bio, prev);
> > +			bio->bi_iter.bi_sector = bio_end_sector(prev);
> > +			bio->bi_opf = prev->bi_opf;
> > +			bio_chain(bio, prev);
> > +
> > +			submit_bio(prev);
> > +		}
> 
> I suspect the problem is here. This chains bios in a different order
> to xfs_chain_bio() in the data writeback path, and it looks to be
> mis-behaving.

DOH.  Yes, it is.

bio_chain(a, b) sets up @a and @b such that when @a completes it'll
decrement @b's remaining count and if that hits zero it also calls @b's
endio function.

So for xfs_rw_bdev, we allocate a bio bio0, point the local variable
*bio at bio0, and enter the outer do-while loop.  The outer loop body
adds pages to bio0.  At some point the inner while loop conditional
becomes true (i.e. we failed to add the page) so we enter the inner loop
body.  The inner loop body creates bio1, chains bio1 to bio0, and
submits bio0.  Now bio1->bi_end_io == bio_chain_endio and
bio0->bi_end_io == NULL.  The local variable *bio now points to bio1.

Presumably we run through the outer loop at least one more time, adding
more pages to *bio (which points to bio1).  When we exit the outer loop,
we then call submit_bio_wait(bio), which actually calls submit_bio_wait
on bio1.

submit_bio_wait(b) sets @b->bi_end_io to submit_bio_wait_endio, submits
@b, and waits for it to complete.

OOOPS.

The submit_bio_wait blows away our old assignment of bio1->bi_end_io ==
bio_chain_endio and replaces it with submit_bio_wait_endio.  So
xfs_rw_bdev waits /only/ for bio1 to finish and exits without waiting
for bio0, and if you're lucky bio0 completes soon enough that the caller
doesn't notice.  AFAICT, I think bio0 just leaks.

So I think the solution is that we have to call submit_bio_wait on that
very first bio (bio0) since the bios created in the inner loop will be
chained to it... ?  Thoughts/flames/"go finish your morning coffee"?

--D

> The tracing I have shows this interesting case right before we hit
> the bad state:
> 
>     53.622521: bprint:               xlog_find_zeroed: first_cycle 0x1
>     53.623277: bprint:               xlog_find_zeroed: last_cycle 0x0
>     53.633060: bprint:               xlog_find_zeroed: start_blk 0xf0, last_blk 0x10f0
>     53.633320: bprint:               xlog_find_verify_cycle: bufblks 0x2000
> 
> And the I/O that is now issued by xlog_find_verify_cycle() is:
> 
>     53.633321: bprint:               xfs_rw_bdev: s 0xa00140, c 0x200000, op 0
> 
> for 2MB of log space to see if there's any holes in the iclog range
> prior to the last cycle change. THis is issued as two bios:
> 
>     53.633340: bprint:               xfs_rw_bdev: sb prev s 0xa00140 0xa00d10
>     53.633340: block_bio_queue:      8,80 RSM 10486080 + 3024 [mount]
> 
> The first is 3024 sectors in length
> 
>     53.633350: block_split:          8,80 RSM 10486080 / 10488640 [mount]
> 
> which we chain to our next bio and submit it. It is then split
> and chained in the block layer
> 
>     53.633352: block_getrq:          8,80 RSM 10486080 + 2560 [mount]
>     53.633353: block_rq_insert:      8,80 RSM 1310720 () 10486080 + 2560 [mount]
>     53.633362: block_rq_issue:       8,80 RSM 1310720 () 10486080 + 2560 [kworker/3:1H]
>     53.633418: block_getrq:          8,80 RSM 10488640 + 464 [mount]
>     53.633420: block_rq_insert:      8,80 RSM 237568 () 10488640 + 464 [mount]
>     53.633426: block_rq_issue:       8,80 RSM 237568 () 10488640 + 464 [kworker/3:1H]
> 
> and both bios are issued, and then:
> 
> > +
> > +		data += len;
> > +		left -= len;
> > +	} while (left > 0);
> > +
> > +	error = submit_bio_wait(bio);
> > +	bio_put(bio);
> 
>     53.633465: bprint:               xfs_rw_bdev: sbw s 0xa00d10 0xa01140
>     53.633466: block_bio_queue:      8,80 RSM 10489104 + 1072 [mount]
> 
> we submit our second bio and wait on it to complete.
> 
>     53.633471: block_getrq:          8,80 RSM 10489104 + 1072 [mount]
>     53.633472: block_rq_insert:      8,80 RSM 548864 () 10489104 + 1072 [mount]
>     53.633478: block_rq_issue:       8,80 RSM 548864 () 10489104 + 1072 [kworker/3:1H]
>     53.636267: block_rq_complete:    8,80 RSM () 10488640 + 464 [0]
>     53.640807: block_rq_complete:    8,80 RSM () 10489104 + 1072 [0]
> 
> So at this point the smaller split bio has completed, as has the second
> bio we called submit_bio_wait() on, but the next trace:
> 
>     53.640987: bprint:               xlog_find_zeroed: new_blk 0x10c, last_blk 0x10c
> 
> Indicates that submit_bio_wait has completed. The first part of the
> split bio hasn't completed yet, so we have undefined contents in the
> buffer and it finds a zero cycle in the range we were searching. So,
> we call into xlog_find_verify_log_record() which issues new IO at
> the start of the range:
> 
>     53.640990: bprint:               xfs_rw_bdev: s 0xa00140, c 0x4000, op 0
>     53.640992: bprint:               xfs_rw_bdev: sbw s 0xa00140 0xa00160
>     53.640993: block_bio_queue:      8,80 RSM 10486080 + 32 [mount]
>     53.640997: block_getrq:          8,80 RSM 10486080 + 32 [mount]
>     53.640998: block_rq_insert:      8,80 RSM 16384 () 10486080 + 32 [mount]
>     53.641010: block_rq_issue:       8,80 RSM 16384 () 10486080 + 32 [kworker/3:1H]
> 
> And then we see this happen:
> 
>     53.651936: block_rq_complete:    8,80 RSM () 10486080 + 2560 [0]
>     53.652033: block_rq_complete:    8,80 RSM () 10486080 + 32 [0]
> 
> There's two completions for overlapping IOs, and one of them is the
> remaining bio that was split in the block layer. And because when we
> actually read that record, we don't find a cycle number change in it
> or even a complete log record, we get this:
> 
>     53.652058: console:              [   53.491104] XFS (sdf): Log inconsistent (didn't find previous header)
>     53.653500: console:              [   53.492547] XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 474
> 
> The assert fires.
> 
> It looks like blk_split_request() has corrupted out bio chain by
> splitting a bio in the chain and not linking it back together
> correctly.
> 
> It's not exactly clear to me how nested bio chaining like this is
> supposed to work, but it looks to me like it is the source of the
> log recovery corruption I'm seeing here...
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Christoph Hellwig]

On Mon, Jul 08, 2019 at 09:19:19AM -0700, Darrick J. Wong wrote:
> The submit_bio_wait blows away our old assignment of bio1->bi_end_io ==
> bio_chain_endio and replaces it with submit_bio_wait_endio.  So
> xfs_rw_bdev waits /only/ for bio1 to finish and exits without waiting
> for bio0, and if you're lucky bio0 completes soon enough that the caller
> doesn't notice.  AFAICT, I think bio0 just leaks.
> 
> So I think the solution is that we have to call submit_bio_wait on that
> very first bio (bio0) since the bios created in the inner loop will be
> chained to it... ?  Thoughts/flames/"go finish your morning coffee"?

I'm going to finish my morning coffee first given that I'm on pacific
time at the moment, but the analysis sounds relatively sane.

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Christoph Hellwig]

On Mon, Jul 08, 2019 at 09:19:19AM -0700, Darrick J. Wong wrote:
> So I think the solution is that we have to call submit_bio_wait on that
> very first bio (bio0) since the bios created in the inner loop will be
> chained to it... ?  Thoughts/flames/"go finish your morning coffee"?

I think we could also just turn the direction of the chaining around,
then the newly allocated bio is the "parent" to the previous one and
we can simply wait for the last one.  Something like the patch below,
running it through xfstests now, and then after that I'll add a way
to inject chaining even into relatively small I/Os to actually
test this code path:

diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
index 757c1d9293eb..e2148f2d5d6b 100644
--- a/fs/xfs/xfs_bio_io.c
+++ b/fs/xfs/xfs_bio_io.c
@@ -43,7 +43,7 @@ xfs_rw_bdev(
 			bio_copy_dev(bio, prev);
 			bio->bi_iter.bi_sector = bio_end_sector(prev);
 			bio->bi_opf = prev->bi_opf;
-			bio_chain(bio, prev);
+			bio_chain(prev, bio);
 
 			submit_bio(prev);
 		}

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Dave Chinner]

On Mon, Jul 08, 2019 at 11:34:23PM +0200, Christoph Hellwig wrote:
> On Mon, Jul 08, 2019 at 09:19:19AM -0700, Darrick J. Wong wrote:
> > So I think the solution is that we have to call submit_bio_wait on that
> > very first bio (bio0) since the bios created in the inner loop will be
> > chained to it... ?  Thoughts/flames/"go finish your morning coffee"?
> 
> I think we could also just turn the direction of the chaining around,
> then the newly allocated bio is the "parent" to the previous one and
> we can simply wait for the last one.  Something like the patch below,
> running it through xfstests now, and then after that I'll add a way
> to inject chaining even into relatively small I/Os to actually
> test this code path:
> 
> diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
> index 757c1d9293eb..e2148f2d5d6b 100644
> --- a/fs/xfs/xfs_bio_io.c
> +++ b/fs/xfs/xfs_bio_io.c
> @@ -43,7 +43,7 @@ xfs_rw_bdev(
>  			bio_copy_dev(bio, prev);
>  			bio->bi_iter.bi_sector = bio_end_sector(prev);
>  			bio->bi_opf = prev->bi_opf;
> -			bio_chain(bio, prev);
> +			bio_chain(prev, bio);

That fixes the problem I saw, but I think bio_chain() needs some
more checks to prevent this happening in future. It's trivially
easy to chain the bios in the wrong order, very difficult to spot
in review, and difficult to trigger in testing as it requires
chain nesting and adverse IO timing to expose....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Christoph Hellwig]

On Tue, Jul 09, 2019 at 08:15:08AM +1000, Dave Chinner wrote:
> That fixes the problem I saw, but I think bio_chain() needs some
> more checks to prevent this happening in future. It's trivially
> easy to chain the bios in the wrong order, very difficult to spot
> in review, and difficult to trigger in testing as it requires
> chain nesting and adverse IO timing to expose....

Not sure how we can better check it.  At best we can set a flag for a
bio that is a chain "child" and complain if someone is calling
submit_bio_wait, but that would only really cover the wait case.

But one thing I planned to do is to lift xfs_chain_bio to the block
layer so that people can use it for any kind of continuation bio
instead of duplicating the logic.

Re: [PATCH 19/24] xfs: use bios directly to read and write the log recovery buffers

[Darrick J. Wong]

On Tue, Jul 09, 2019 at 05:23:30PM +0200, Christoph Hellwig wrote:
> On Tue, Jul 09, 2019 at 08:15:08AM +1000, Dave Chinner wrote:
> > That fixes the problem I saw, but I think bio_chain() needs some
> > more checks to prevent this happening in future. It's trivially
> > easy to chain the bios in the wrong order, very difficult to spot
> > in review, and difficult to trigger in testing as it requires
> > chain nesting and adverse IO timing to expose....
> 
> Not sure how we can better check it.  At best we can set a flag for a
> bio that is a chain "child" and complain if someone is calling
> submit_bio_wait, but that would only really cover the wait case.

I think submit_bio_wait ought to at least WARN_ON_ONCE if it was fed a
bio with bi_end_io already set, which at least would have made it more
obvious that we'd screwed something up in this case, even if the
detection was after we'd already done bio_chain in the wrong order.

Granted IIRC Dave sent a fix for a zeroout integer overflow a while ago
and Jens committed the patch with the debugging assertions removed, so
... yay?

Maybe we just need CONFIG_BLK_DEBUG for these kinds of assertions so
that ignorant clods like me have another line of defense against bugs
and the growing crowd of people who care about performance above
correctness can crash faster. <grumble>

> But one thing I planned to do is to lift xfs_chain_bio to the block
> layer so that people can use it for any kind of continuation bio
> instead of duplicating the logic.

That'll help, I suspect. :)

--D

[PATCH 20/24] xfs: stop using bp naming for log recovery buffers

[Christoph Hellwig]

Now that we don't use struct xfs_buf to hold log recovery buffer rename
the related functions and variables to just talk of a buffer instead of
using the bp name that we usually use for xfs_buf related functionality.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log_recover.c | 201 ++++++++++++++++++++-------------------
 1 file changed, 102 insertions(+), 99 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index a28c9dc8f1f2..403c2c96ed71 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -79,7 +79,7 @@ struct xfs_buf_cancel {
  * are valid, false otherwise.
  */
 static inline bool
-xlog_verify_bp(
+xlog_verify_bno(
 	struct xlog	*log,
 	xfs_daddr_t	blk_no,
 	int		bbcount)
@@ -96,7 +96,7 @@ xlog_verify_bp(
  * a range of nbblks basic blocks at any valid offset within the log.
  */
 static char *
-xlog_get_bp(
+xlog_alloc_buffer(
 	struct xlog	*log,
 	int		nbblks)
 {
@@ -104,7 +104,7 @@ xlog_get_bp(
 	 * Pass log block 0 since we don't have an addr yet, buffer will be
 	 * verified on read.
 	 */
-	if (!xlog_verify_bp(log, 0, nbblks)) {
+	if (!xlog_verify_bno(log, 0, nbblks)) {
 		xfs_warn(log->l_mp, "Invalid block length (0x%x) for buffer",
 			nbblks);
 		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_HIGH, log->l_mp);
@@ -153,7 +153,7 @@ xlog_do_io(
 {
 	int			error;
 
-	if (!xlog_verify_bp(log, blk_no, nbblks)) {
+	if (!xlog_verify_bno(log, blk_no, nbblks)) {
 		xfs_warn(log->l_mp,
 			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
 			 blk_no, nbblks);
@@ -327,7 +327,7 @@ xlog_recover_iodone(
 STATIC int
 xlog_find_cycle_start(
 	struct xlog	*log,
-	char		*bp,
+	char		*buffer,
 	xfs_daddr_t	first_blk,
 	xfs_daddr_t	*last_blk,
 	uint		cycle)
@@ -341,7 +341,7 @@ xlog_find_cycle_start(
 	end_blk = *last_blk;
 	mid_blk = BLK_AVG(first_blk, end_blk);
 	while (mid_blk != first_blk && mid_blk != end_blk) {
-		error = xlog_bread(log, mid_blk, 1, bp, &offset);
+		error = xlog_bread(log, mid_blk, 1, buffer, &offset);
 		if (error)
 			return error;
 		mid_cycle = xlog_get_cycle(offset);
@@ -377,7 +377,7 @@ xlog_find_verify_cycle(
 {
 	xfs_daddr_t	i, j;
 	uint		cycle;
-	char		*bp;
+	char		*buffer;
 	xfs_daddr_t	bufblks;
 	char		*buf = NULL;
 	int		error = 0;
@@ -391,7 +391,7 @@ xlog_find_verify_cycle(
 	bufblks = 1 << ffs(nbblks);
 	while (bufblks > log->l_logBBsize)
 		bufblks >>= 1;
-	while (!(bp = xlog_get_bp(log, bufblks))) {
+	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
 		bufblks >>= 1;
 		if (bufblks < log->l_sectBBsize)
 			return -ENOMEM;
@@ -402,7 +402,7 @@ xlog_find_verify_cycle(
 
 		bcount = min(bufblks, (start_blk + nbblks - i));
 
-		error = xlog_bread(log, i, bcount, bp, &buf);
+		error = xlog_bread(log, i, bcount, buffer, &buf);
 		if (error)
 			goto out;
 
@@ -420,7 +420,7 @@ xlog_find_verify_cycle(
 	*new_blk = -1;
 
 out:
-	kmem_free(bp);
+	kmem_free(buffer);
 	return error;
 }
 
@@ -444,7 +444,7 @@ xlog_find_verify_log_record(
 	int			extra_bblks)
 {
 	xfs_daddr_t		i;
-	char			*bp;
+	char			*buffer;
 	char			*offset = NULL;
 	xlog_rec_header_t	*head = NULL;
 	int			error = 0;
@@ -454,12 +454,14 @@ xlog_find_verify_log_record(
 
 	ASSERT(start_blk != 0 || *last_blk != start_blk);
 
-	if (!(bp = xlog_get_bp(log, num_blks))) {
-		if (!(bp = xlog_get_bp(log, 1)))
+	buffer = xlog_alloc_buffer(log, num_blks);
+	if (!buffer) {
+		buffer = xlog_alloc_buffer(log, 1);
+		if (!buffer)
 			return -ENOMEM;
 		smallmem = 1;
 	} else {
-		error = xlog_bread(log, start_blk, num_blks, bp, &offset);
+		error = xlog_bread(log, start_blk, num_blks, buffer, &offset);
 		if (error)
 			goto out;
 		offset += ((num_blks - 1) << BBSHIFT);
@@ -476,7 +478,7 @@ xlog_find_verify_log_record(
 		}
 
 		if (smallmem) {
-			error = xlog_bread(log, i, 1, bp, &offset);
+			error = xlog_bread(log, i, 1, buffer, &offset);
 			if (error)
 				goto out;
 		}
@@ -529,7 +531,7 @@ xlog_find_verify_log_record(
 		*last_blk = i;
 
 out:
-	kmem_free(bp);
+	kmem_free(buffer);
 	return error;
 }
 
@@ -551,7 +553,7 @@ xlog_find_head(
 	struct xlog	*log,
 	xfs_daddr_t	*return_head_blk)
 {
-	char		*bp;
+	char		*buffer;
 	char		*offset;
 	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
 	int		num_scan_bblks;
@@ -581,20 +583,20 @@ xlog_find_head(
 	}
 
 	first_blk = 0;			/* get cycle # of 1st block */
-	bp = xlog_get_bp(log, 1);
-	if (!bp)
+	buffer = xlog_alloc_buffer(log, 1);
+	if (!buffer)
 		return -ENOMEM;
 
-	error = xlog_bread(log, 0, 1, bp, &offset);
+	error = xlog_bread(log, 0, 1, buffer, &offset);
 	if (error)
-		goto bp_err;
+		goto out_free_buffer;
 
 	first_half_cycle = xlog_get_cycle(offset);
 
 	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
-	error = xlog_bread(log, last_blk, 1, bp, &offset);
+	error = xlog_bread(log, last_blk, 1, buffer, &offset);
 	if (error)
-		goto bp_err;
+		goto out_free_buffer;
 
 	last_half_cycle = xlog_get_cycle(offset);
 	ASSERT(last_half_cycle != 0);
@@ -662,9 +664,10 @@ xlog_find_head(
 		 *                           ^ we want to locate this spot
 		 */
 		stop_on_cycle = last_half_cycle;
-		if ((error = xlog_find_cycle_start(log, bp, first_blk,
-						&head_blk, last_half_cycle)))
-			goto bp_err;
+		error = xlog_find_cycle_start(log, buffer, first_blk, &head_blk,
+				last_half_cycle);
+		if (error)
+			goto out_free_buffer;
 	}
 
 	/*
@@ -684,7 +687,7 @@ xlog_find_head(
 		if ((error = xlog_find_verify_cycle(log,
 						start_blk, num_scan_bblks,
 						stop_on_cycle, &new_blk)))
-			goto bp_err;
+			goto out_free_buffer;
 		if (new_blk != -1)
 			head_blk = new_blk;
 	} else {		/* need to read 2 parts of log */
@@ -721,7 +724,7 @@ xlog_find_head(
 		if ((error = xlog_find_verify_cycle(log, start_blk,
 					num_scan_bblks - (int)head_blk,
 					(stop_on_cycle - 1), &new_blk)))
-			goto bp_err;
+			goto out_free_buffer;
 		if (new_blk != -1) {
 			head_blk = new_blk;
 			goto validate_head;
@@ -737,7 +740,7 @@ xlog_find_head(
 		if ((error = xlog_find_verify_cycle(log,
 					start_blk, (int)head_blk,
 					stop_on_cycle, &new_blk)))
-			goto bp_err;
+			goto out_free_buffer;
 		if (new_blk != -1)
 			head_blk = new_blk;
 	}
@@ -756,13 +759,13 @@ xlog_find_head(
 		if (error == 1)
 			error = -EIO;
 		if (error)
-			goto bp_err;
+			goto out_free_buffer;
 	} else {
 		start_blk = 0;
 		ASSERT(head_blk <= INT_MAX);
 		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
 		if (error < 0)
-			goto bp_err;
+			goto out_free_buffer;
 		if (error == 1) {
 			/* We hit the beginning of the log during our search */
 			start_blk = log_bbnum - (num_scan_bblks - head_blk);
@@ -775,14 +778,14 @@ xlog_find_head(
 			if (error == 1)
 				error = -EIO;
 			if (error)
-				goto bp_err;
+				goto out_free_buffer;
 			if (new_blk != log_bbnum)
 				head_blk = new_blk;
 		} else if (error)
-			goto bp_err;
+			goto out_free_buffer;
 	}
 
-	kmem_free(bp);
+	kmem_free(buffer);
 	if (head_blk == log_bbnum)
 		*return_head_blk = 0;
 	else
@@ -795,9 +798,8 @@ xlog_find_head(
 	 */
 	return 0;
 
- bp_err:
-	kmem_free(bp);
-
+out_free_buffer:
+	kmem_free(buffer);
 	if (error)
 		xfs_warn(log->l_mp, "failed to find log head");
 	return error;
@@ -817,7 +819,7 @@ xlog_rseek_logrec_hdr(
 	xfs_daddr_t		head_blk,
 	xfs_daddr_t		tail_blk,
 	int			count,
-	char			*bp,
+	char			*buffer,
 	xfs_daddr_t		*rblk,
 	struct xlog_rec_header	**rhead,
 	bool			*wrapped)
@@ -836,7 +838,7 @@ xlog_rseek_logrec_hdr(
 	 */
 	end_blk = head_blk > tail_blk ? tail_blk : 0;
 	for (i = (int) head_blk - 1; i >= end_blk; i--) {
-		error = xlog_bread(log, i, 1, bp, &offset);
+		error = xlog_bread(log, i, 1, buffer, &offset);
 		if (error)
 			goto out_error;
 
@@ -855,7 +857,7 @@ xlog_rseek_logrec_hdr(
 	 */
 	if (tail_blk >= head_blk && found != count) {
 		for (i = log->l_logBBsize - 1; i >= (int) tail_blk; i--) {
-			error = xlog_bread(log, i, 1, bp, &offset);
+			error = xlog_bread(log, i, 1, buffer, &offset);
 			if (error)
 				goto out_error;
 
@@ -891,7 +893,7 @@ xlog_seek_logrec_hdr(
 	xfs_daddr_t		head_blk,
 	xfs_daddr_t		tail_blk,
 	int			count,
-	char			*bp,
+	char			*buffer,
 	xfs_daddr_t		*rblk,
 	struct xlog_rec_header	**rhead,
 	bool			*wrapped)
@@ -910,7 +912,7 @@ xlog_seek_logrec_hdr(
 	 */
 	end_blk = head_blk > tail_blk ? head_blk : log->l_logBBsize - 1;
 	for (i = (int) tail_blk; i <= end_blk; i++) {
-		error = xlog_bread(log, i, 1, bp, &offset);
+		error = xlog_bread(log, i, 1, buffer, &offset);
 		if (error)
 			goto out_error;
 
@@ -928,7 +930,7 @@ xlog_seek_logrec_hdr(
 	 */
 	if (tail_blk > head_blk && found != count) {
 		for (i = 0; i < (int) head_blk; i++) {
-			error = xlog_bread(log, i, 1, bp, &offset);
+			error = xlog_bread(log, i, 1, buffer, &offset);
 			if (error)
 				goto out_error;
 
@@ -991,22 +993,22 @@ xlog_verify_tail(
 	int			hsize)
 {
 	struct xlog_rec_header	*thead;
-	char			*bp;
+	char			*buffer;
 	xfs_daddr_t		first_bad;
 	int			error = 0;
 	bool			wrapped;
 	xfs_daddr_t		tmp_tail;
 	xfs_daddr_t		orig_tail = *tail_blk;
 
-	bp = xlog_get_bp(log, 1);
-	if (!bp)
+	buffer = xlog_alloc_buffer(log, 1);
+	if (!buffer)
 		return -ENOMEM;
 
 	/*
 	 * Make sure the tail points to a record (returns positive count on
 	 * success).
 	 */
-	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, bp,
+	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, buffer,
 			&tmp_tail, &thead, &wrapped);
 	if (error < 0)
 		goto out;
@@ -1035,8 +1037,8 @@ xlog_verify_tail(
 			break;
 
 		/* skip to the next record; returns positive count on success */
-		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2, bp,
-				&tmp_tail, &thead, &wrapped);
+		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2,
+				buffer, &tmp_tail, &thead, &wrapped);
 		if (error < 0)
 			goto out;
 
@@ -1051,7 +1053,7 @@ xlog_verify_tail(
 		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
 			 orig_tail, *tail_blk);
 out:
-	kmem_free(bp);
+	kmem_free(buffer);
 	return error;
 }
 
@@ -1073,13 +1075,13 @@ xlog_verify_head(
 	struct xlog		*log,
 	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
 	xfs_daddr_t		*tail_blk,	/* out: tail block */
-	char			*bp,
+	char			*buffer,
 	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
 	struct xlog_rec_header	**rhead,	/* ptr to last record */
 	bool			*wrapped)	/* last rec. wraps phys. log */
 {
 	struct xlog_rec_header	*tmp_rhead;
-	char			*tmp_bp;
+	char			*tmp_buffer;
 	xfs_daddr_t		first_bad;
 	xfs_daddr_t		tmp_rhead_blk;
 	int			found;
@@ -1090,15 +1092,15 @@ xlog_verify_head(
 	 * Check the head of the log for torn writes. Search backwards from the
 	 * head until we hit the tail or the maximum number of log record I/Os
 	 * that could have been in flight at one time. Use a temporary buffer so
-	 * we don't trash the rhead/bp pointers from the caller.
+	 * we don't trash the rhead/buffer pointers from the caller.
 	 */
-	tmp_bp = xlog_get_bp(log, 1);
-	if (!tmp_bp)
+	tmp_buffer = xlog_alloc_buffer(log, 1);
+	if (!tmp_buffer)
 		return -ENOMEM;
 	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
-				      XLOG_MAX_ICLOGS, tmp_bp, &tmp_rhead_blk,
-				      &tmp_rhead, &tmp_wrapped);
-	kmem_free(tmp_bp);
+				      XLOG_MAX_ICLOGS, tmp_buffer,
+				      &tmp_rhead_blk, &tmp_rhead, &tmp_wrapped);
+	kmem_free(tmp_buffer);
 	if (error < 0)
 		return error;
 
@@ -1127,8 +1129,8 @@ xlog_verify_head(
 		 * (i.e., the records with invalid CRC) if the cycle number
 		 * matches the the current cycle.
 		 */
-		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1, bp,
-					      rhead_blk, rhead, wrapped);
+		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1,
+				buffer, rhead_blk, rhead, wrapped);
 		if (found < 0)
 			return found;
 		if (found == 0)		/* XXX: right thing to do here? */
@@ -1188,7 +1190,7 @@ xlog_check_unmount_rec(
 	xfs_daddr_t		*tail_blk,
 	struct xlog_rec_header	*rhead,
 	xfs_daddr_t		rhead_blk,
-	char			*bp,
+	char			*buffer,
 	bool			*clean)
 {
 	struct xlog_op_header	*op_head;
@@ -1231,7 +1233,7 @@ xlog_check_unmount_rec(
 	if (*head_blk == after_umount_blk &&
 	    be32_to_cpu(rhead->h_num_logops) == 1) {
 		umount_data_blk = xlog_wrap_logbno(log, rhead_blk + hblks);
-		error = xlog_bread(log, umount_data_blk, 1, bp, &offset);
+		error = xlog_bread(log, umount_data_blk, 1, buffer, &offset);
 		if (error)
 			return error;
 
@@ -1310,7 +1312,7 @@ xlog_find_tail(
 {
 	xlog_rec_header_t	*rhead;
 	char			*offset = NULL;
-	char			*bp;
+	char			*buffer;
 	int			error;
 	xfs_daddr_t		rhead_blk;
 	xfs_lsn_t		tail_lsn;
@@ -1324,11 +1326,11 @@ xlog_find_tail(
 		return error;
 	ASSERT(*head_blk < INT_MAX);
 
-	bp = xlog_get_bp(log, 1);
-	if (!bp)
+	buffer = xlog_alloc_buffer(log, 1);
+	if (!buffer)
 		return -ENOMEM;
 	if (*head_blk == 0) {				/* special case */
-		error = xlog_bread(log, 0, 1, bp, &offset);
+		error = xlog_bread(log, 0, 1, buffer, &offset);
 		if (error)
 			goto done;
 
@@ -1344,7 +1346,7 @@ xlog_find_tail(
 	 * block. This wraps all the way back around to the head so something is
 	 * seriously wrong if we can't find it.
 	 */
-	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, bp,
+	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, buffer,
 				      &rhead_blk, &rhead, &wrapped);
 	if (error < 0)
 		return error;
@@ -1365,7 +1367,7 @@ xlog_find_tail(
 	 * state to determine whether recovery is necessary.
 	 */
 	error = xlog_check_unmount_rec(log, head_blk, tail_blk, rhead,
-				       rhead_blk, bp, &clean);
+				       rhead_blk, buffer, &clean);
 	if (error)
 		goto done;
 
@@ -1382,7 +1384,7 @@ xlog_find_tail(
 	if (!clean) {
 		xfs_daddr_t	orig_head = *head_blk;
 
-		error = xlog_verify_head(log, head_blk, tail_blk, bp,
+		error = xlog_verify_head(log, head_blk, tail_blk, buffer,
 					 &rhead_blk, &rhead, &wrapped);
 		if (error)
 			goto done;
@@ -1393,7 +1395,7 @@ xlog_find_tail(
 				       wrapped);
 			tail_lsn = atomic64_read(&log->l_tail_lsn);
 			error = xlog_check_unmount_rec(log, head_blk, tail_blk,
-						       rhead, rhead_blk, bp,
+						       rhead, rhead_blk, buffer,
 						       &clean);
 			if (error)
 				goto done;
@@ -1431,7 +1433,7 @@ xlog_find_tail(
 		error = xlog_clear_stale_blocks(log, tail_lsn);
 
 done:
-	kmem_free(bp);
+	kmem_free(buffer);
 
 	if (error)
 		xfs_warn(log->l_mp, "failed to locate log tail");
@@ -1459,7 +1461,7 @@ xlog_find_zeroed(
 	struct xlog	*log,
 	xfs_daddr_t	*blk_no)
 {
-	char		*bp;
+	char		*buffer;
 	char		*offset;
 	uint	        first_cycle, last_cycle;
 	xfs_daddr_t	new_blk, last_blk, start_blk;
@@ -1469,35 +1471,36 @@ xlog_find_zeroed(
 	*blk_no = 0;
 
 	/* check totally zeroed log */
-	bp = xlog_get_bp(log, 1);
-	if (!bp)
+	buffer = xlog_alloc_buffer(log, 1);
+	if (!buffer)
 		return -ENOMEM;
-	error = xlog_bread(log, 0, 1, bp, &offset);
+	error = xlog_bread(log, 0, 1, buffer, &offset);
 	if (error)
-		goto bp_err;
+		goto out_free_buffer;
 
 	first_cycle = xlog_get_cycle(offset);
 	if (first_cycle == 0) {		/* completely zeroed log */
 		*blk_no = 0;
-		kmem_free(bp);
+		kmem_free(buffer);
 		return 1;
 	}
 
 	/* check partially zeroed log */
-	error = xlog_bread(log, log_bbnum-1, 1, bp, &offset);
+	error = xlog_bread(log, log_bbnum-1, 1, buffer, &offset);
 	if (error)
-		goto bp_err;
+		goto out_free_buffer;
 
 	last_cycle = xlog_get_cycle(offset);
 	if (last_cycle != 0) {		/* log completely written to */
-		kmem_free(bp);
+		kmem_free(buffer);
 		return 0;
 	}
 
 	/* we have a partially zeroed log */
 	last_blk = log_bbnum-1;
-	if ((error = xlog_find_cycle_start(log, bp, 0, &last_blk, 0)))
-		goto bp_err;
+	error = xlog_find_cycle_start(log, buffer, 0, &last_blk, 0);
+	if (error)
+		goto out_free_buffer;
 
 	/*
 	 * Validate the answer.  Because there is no way to guarantee that
@@ -1520,7 +1523,7 @@ xlog_find_zeroed(
 	 */
 	if ((error = xlog_find_verify_cycle(log, start_blk,
 					 (int)num_scan_bblks, 0, &new_blk)))
-		goto bp_err;
+		goto out_free_buffer;
 	if (new_blk != -1)
 		last_blk = new_blk;
 
@@ -1532,11 +1535,11 @@ xlog_find_zeroed(
 	if (error == 1)
 		error = -EIO;
 	if (error)
-		goto bp_err;
+		goto out_free_buffer;
 
 	*blk_no = last_blk;
-bp_err:
-	kmem_free(bp);
+out_free_buffer:
+	kmem_free(buffer);
 	if (error)
 		return error;
 	return 1;
@@ -1579,7 +1582,7 @@ xlog_write_log_records(
 	int		tail_block)
 {
 	char		*offset;
-	char		*bp;
+	char		*buffer;
 	int		balign, ealign;
 	int		sectbb = log->l_sectBBsize;
 	int		end_block = start_block + blocks;
@@ -1596,7 +1599,7 @@ xlog_write_log_records(
 	bufblks = 1 << ffs(blocks);
 	while (bufblks > log->l_logBBsize)
 		bufblks >>= 1;
-	while (!(bp = xlog_get_bp(log, bufblks))) {
+	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
 		bufblks >>= 1;
 		if (bufblks < sectbb)
 			return -ENOMEM;
@@ -1608,9 +1611,9 @@ xlog_write_log_records(
 	 */
 	balign = round_down(start_block, sectbb);
 	if (balign != start_block) {
-		error = xlog_bread_noalign(log, start_block, 1, bp);
+		error = xlog_bread_noalign(log, start_block, 1, buffer);
 		if (error)
-			goto out_put_bp;
+			goto out_free_buffer;
 
 		j = start_block - balign;
 	}
@@ -1628,27 +1631,27 @@ xlog_write_log_records(
 		ealign = round_down(end_block, sectbb);
 		if (j == 0 && (start_block + endcount > ealign)) {
 			error = xlog_bread_noalign(log, ealign, sectbb,
-					bp + BBTOB(ealign - start_block));
+					buffer + BBTOB(ealign - start_block));
 			if (error)
 				break;
 
 		}
 
-		offset = bp + xlog_align(log, start_block);
+		offset = buffer + xlog_align(log, start_block);
 		for (; j < endcount; j++) {
 			xlog_add_record(log, offset, cycle, i+j,
 					tail_cycle, tail_block);
 			offset += BBSIZE;
 		}
-		error = xlog_bwrite(log, start_block, endcount, bp);
+		error = xlog_bwrite(log, start_block, endcount, buffer);
 		if (error)
 			break;
 		start_block += endcount;
 		j = 0;
 	}
 
- out_put_bp:
-	kmem_free(bp);
+out_free_buffer:
+	kmem_free(buffer);
 	return error;
 }
 
@@ -5253,7 +5256,7 @@ xlog_do_recovery_pass(
 		 * iclog header and extract the header size from it.  Get a
 		 * new hbp that is the correct size.
 		 */
-		hbp = xlog_get_bp(log, 1);
+		hbp = xlog_alloc_buffer(log, 1);
 		if (!hbp)
 			return -ENOMEM;
 
@@ -5296,20 +5299,20 @@ xlog_do_recovery_pass(
 			if (h_size % XLOG_HEADER_CYCLE_SIZE)
 				hblks++;
 			kmem_free(hbp);
-			hbp = xlog_get_bp(log, hblks);
+			hbp = xlog_alloc_buffer(log, hblks);
 		} else {
 			hblks = 1;
 		}
 	} else {
 		ASSERT(log->l_sectBBsize == 1);
 		hblks = 1;
-		hbp = xlog_get_bp(log, 1);
+		hbp = xlog_alloc_buffer(log, 1);
 		h_size = XLOG_BIG_RECORD_BSIZE;
 	}
 
 	if (!hbp)
 		return -ENOMEM;
-	dbp = xlog_get_bp(log, BTOBB(h_size));
+	dbp = xlog_alloc_buffer(log, BTOBB(h_size));
 	if (!dbp) {
 		kmem_free(hbp);
 		return -ENOMEM;
-- 
2.20.1

[PATCH 21/24] xfs: remove unused buffer cache APIs

[Christoph Hellwig]

Now that the log code uses bios directly we can drop various special
cases in the buffer cache code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c | 83 ++----------------------------------------------
 fs/xfs/xfs_buf.h | 27 ----------------
 2 files changed, 2 insertions(+), 108 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index ade6ec28e1c9..68444d20d2ed 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -213,7 +213,7 @@ xfs_buf_free_maps(
 	}
 }
 
-struct xfs_buf *
+static struct xfs_buf *
 _xfs_buf_alloc(
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
@@ -909,72 +909,6 @@ xfs_buf_read_uncached(
 	return 0;
 }
 
-/*
- * Return a buffer allocated as an empty buffer and associated to external
- * memory via xfs_buf_associate_memory() back to it's empty state.
- */
-void
-xfs_buf_set_empty(
-	struct xfs_buf		*bp,
-	size_t			numblks)
-{
-	if (bp->b_pages)
-		_xfs_buf_free_pages(bp);
-
-	bp->b_pages = NULL;
-	bp->b_page_count = 0;
-	bp->b_addr = NULL;
-	bp->b_length = numblks;
-	bp->b_io_length = numblks;
-
-	ASSERT(bp->b_map_count == 1);
-	bp->b_bn = XFS_BUF_DADDR_NULL;
-	bp->b_maps[0].bm_bn = XFS_BUF_DADDR_NULL;
-	bp->b_maps[0].bm_len = bp->b_length;
-}
-
-int
-xfs_buf_associate_memory(
-	xfs_buf_t		*bp,
-	void			*mem,
-	size_t			len)
-{
-	int			rval;
-	int			i = 0;
-	unsigned long		pageaddr;
-	unsigned long		offset;
-	size_t			buflen;
-	int			page_count;
-
-	pageaddr = (unsigned long)mem & PAGE_MASK;
-	offset = (unsigned long)mem - pageaddr;
-	buflen = PAGE_ALIGN(len + offset);
-	page_count = buflen >> PAGE_SHIFT;
-
-	/* Free any previous set of page pointers */
-	if (bp->b_pages)
-		_xfs_buf_free_pages(bp);
-
-	bp->b_pages = NULL;
-	bp->b_addr = mem;
-
-	rval = _xfs_buf_get_pages(bp, page_count);
-	if (rval)
-		return rval;
-
-	bp->b_offset = offset;
-
-	for (i = 0; i < bp->b_page_count; i++) {
-		bp->b_pages[i] = kmem_to_page((void *)pageaddr);
-		pageaddr += PAGE_SIZE;
-	}
-
-	bp->b_io_length = BTOBB(len);
-	bp->b_length = BTOBB(buflen);
-
-	return 0;
-}
-
 xfs_buf_t *
 xfs_buf_get_uncached(
 	struct xfs_buftarg	*target,
@@ -1258,7 +1192,7 @@ xfs_buf_ioend_async(
 	struct xfs_buf	*bp)
 {
 	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
-	queue_work(bp->b_ioend_wq, &bp->b_ioend_work);
+	queue_work(bp->b_target->bt_mount->m_buf_workqueue, &bp->b_ioend_work);
 }
 
 void
@@ -1425,21 +1359,8 @@ _xfs_buf_ioapply(
 	 */
 	bp->b_error = 0;
 
-	/*
-	 * Initialize the I/O completion workqueue if we haven't yet or the
-	 * submitter has not opted to specify a custom one.
-	 */
-	if (!bp->b_ioend_wq)
-		bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue;
-
 	if (bp->b_flags & XBF_WRITE) {
 		op = REQ_OP_WRITE;
-		if (bp->b_flags & XBF_SYNCIO)
-			op_flags = REQ_SYNC;
-		if (bp->b_flags & XBF_FUA)
-			op_flags |= REQ_FUA;
-		if (bp->b_flags & XBF_FLUSH)
-			op_flags |= REQ_PREFLUSH;
 
 		/*
 		 * Run the write verifier callback function if it exists. If
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 15f6ce3974ac..c1965c7e76bb 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -36,11 +36,6 @@ typedef enum {
 #define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
 #define XBF_WRITE_FAIL	 (1 << 7) /* async writes have failed on this buffer */
 
-/* I/O hints for the BIO layer */
-#define XBF_SYNCIO	 (1 << 10)/* treat this buffer as synchronous I/O */
-#define XBF_FUA		 (1 << 11)/* force cache write through mode */
-#define XBF_FLUSH	 (1 << 12)/* flush the disk cache before a write */
-
 /* flags used only as arguments to access routines */
 #define XBF_TRYLOCK	 (1 << 16)/* lock requested, but do not wait */
 #define XBF_UNMAPPED	 (1 << 17)/* do not map the buffer */
@@ -61,9 +56,6 @@ typedef unsigned int xfs_buf_flags_t;
 	{ XBF_DONE,		"DONE" }, \
 	{ XBF_STALE,		"STALE" }, \
 	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
-	{ XBF_SYNCIO,		"SYNCIO" }, \
-	{ XBF_FUA,		"FUA" }, \
-	{ XBF_FLUSH,		"FLUSH" }, \
 	{ XBF_TRYLOCK,		"TRYLOCK" },	/* should never be set */\
 	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
 	{ _XBF_PAGES,		"PAGES" }, \
@@ -162,7 +154,6 @@ typedef struct xfs_buf {
 	xfs_buftarg_t		*b_target;	/* buffer target (device) */
 	void			*b_addr;	/* virtual address of buffer */
 	struct work_struct	b_ioend_work;
-	struct workqueue_struct	*b_ioend_wq;	/* I/O completion wq */
 	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
 	struct completion	b_iowait;	/* queue for I/O waiters */
 	void			*b_log_item;
@@ -207,21 +198,6 @@ struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
 			   xfs_daddr_t blkno, size_t numblks,
 			   xfs_buf_flags_t flags);
 
-struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
-			       struct xfs_buf_map *map, int nmaps,
-			       xfs_buf_flags_t flags);
-
-static inline struct xfs_buf *
-xfs_buf_alloc(
-	struct xfs_buftarg	*target,
-	xfs_daddr_t		blkno,
-	size_t			numblks,
-	xfs_buf_flags_t		flags)
-{
-	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
-	return _xfs_buf_alloc(target, &map, 1, flags);
-}
-
 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 			       struct xfs_buf_map *map, int nmaps,
 			       xfs_buf_flags_t flags);
@@ -267,9 +243,6 @@ xfs_buf_readahead(
 	return xfs_buf_readahead_map(target, &map, 1, ops);
 }
 
-void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
-int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
-
 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 				int flags);
 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
-- 
2.20.1

[PATCH 22/24] xfs: properly type the b_log_item field in struct xfs_buf

[Christoph Hellwig]

Now that the log code doesn't abuse this field any more we can
declare it as a struct xfs_buf_log_item pointer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index c1965c7e76bb..2abd2435d6aa 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -156,7 +156,7 @@ typedef struct xfs_buf {
 	struct work_struct	b_ioend_work;
 	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
 	struct completion	b_iowait;	/* queue for I/O waiters */
-	void			*b_log_item;
+	struct xfs_buf_log_item	*b_log_item;
 	struct list_head	b_li_list;	/* Log items list head */
 	struct xfs_trans	*b_transp;
 	struct page		**b_pages;	/* array of page pointers */
-- 
2.20.1

[PATCH 23/24] xfs: remove the b_io_length field in struct xfs_buf

[Christoph Hellwig]

This field is now always idential to b_length.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c         | 5 ++---
 fs/xfs/xfs_buf.h         | 1 -
 fs/xfs/xfs_log_recover.c | 9 ++++-----
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 68444d20d2ed..26027a93bdd3 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -263,7 +263,6 @@ _xfs_buf_alloc(
 		bp->b_maps[i].bm_len = map[i].bm_len;
 		bp->b_length += map[i].bm_len;
 	}
-	bp->b_io_length = bp->b_length;
 
 	atomic_set(&bp->b_pin_count, 0);
 	init_waitqueue_head(&bp->b_waiters);
@@ -1407,7 +1406,7 @@ _xfs_buf_ioapply(
 	 * subsequent call.
 	 */
 	offset = bp->b_offset;
-	size = BBTOB(bp->b_io_length);
+	size = BBTOB(bp->b_length);
 	blk_start_plug(&plug);
 	for (i = 0; i < bp->b_map_count; i++) {
 		xfs_buf_ioapply_map(bp, i, &offset, &size, op, op_flags);
@@ -1545,7 +1544,7 @@ xfs_buf_iomove(
 		page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
 		page = bp->b_pages[page_index];
 		csize = min_t(size_t, PAGE_SIZE - page_offset,
-				      BBTOB(bp->b_io_length) - boff);
+				      BBTOB(bp->b_length) - boff);
 
 		ASSERT((csize + page_offset) <= PAGE_SIZE);
 
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 2abd2435d6aa..f95cf810126e 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -164,7 +164,6 @@ typedef struct xfs_buf {
 	struct xfs_buf_map	*b_maps;	/* compound buffer map */
 	struct xfs_buf_map	__b_map;	/* inline compound buffer map */
 	int			b_map_count;
-	int			b_io_length;	/* IO size in BBs */
 	atomic_t		b_pin_count;	/* pin count */
 	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
 	unsigned int		b_page_count;	/* size of page array */
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 403c2c96ed71..bbe5e38e2932 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2086,7 +2086,7 @@ xlog_recover_do_inode_buffer(
 	if (xfs_sb_version_hascrc(&mp->m_sb))
 		bp->b_ops = &xfs_inode_buf_ops;
 
-	inodes_per_buf = BBTOB(bp->b_io_length) >> mp->m_sb.sb_inodelog;
+	inodes_per_buf = BBTOB(bp->b_length) >> mp->m_sb.sb_inodelog;
 	for (i = 0; i < inodes_per_buf; i++) {
 		next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
 			offsetof(xfs_dinode_t, di_next_unlinked);
@@ -2128,8 +2128,7 @@ xlog_recover_do_inode_buffer(
 
 		ASSERT(item->ri_buf[item_index].i_addr != NULL);
 		ASSERT((item->ri_buf[item_index].i_len % XFS_BLF_CHUNK) == 0);
-		ASSERT((reg_buf_offset + reg_buf_bytes) <=
-							BBTOB(bp->b_io_length));
+		ASSERT((reg_buf_offset + reg_buf_bytes) <= BBTOB(bp->b_length));
 
 		/*
 		 * The current logged region contains a copy of the
@@ -2594,7 +2593,7 @@ xlog_recover_do_reg_buffer(
 		ASSERT(nbits > 0);
 		ASSERT(item->ri_buf[i].i_addr != NULL);
 		ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
-		ASSERT(BBTOB(bp->b_io_length) >=
+		ASSERT(BBTOB(bp->b_length) >=
 		       ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));
 
 		/*
@@ -2817,7 +2816,7 @@ xlog_recover_buffer_pass2(
 	 */
 	if (XFS_DINODE_MAGIC ==
 	    be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
-	    (BBTOB(bp->b_io_length) != max(log->l_mp->m_sb.sb_blocksize,
+	    (BBTOB(bp->b_length) != max(log->l_mp->m_sb.sb_blocksize,
 			(uint32_t)log->l_mp->m_inode_cluster_size))) {
 		xfs_buf_stale(bp);
 		error = xfs_bwrite(bp);
-- 
2.20.1

[PATCH 24/24] xfs: add struct xfs_mount pointer to struct xfs_buf

[Christoph Hellwig]

We need to derive the mount pointer from a buffer in a lot of place.
Add a direct pointer to short cut the pointer chasing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 .../xfs-self-describing-metadata.txt          |  8 ++---
 fs/xfs/libxfs/xfs_alloc.c                     | 12 +++----
 fs/xfs/libxfs/xfs_alloc_btree.c               |  2 +-
 fs/xfs/libxfs/xfs_attr_leaf.c                 | 12 +++----
 fs/xfs/libxfs/xfs_attr_remote.c               |  4 +--
 fs/xfs/libxfs/xfs_bmap_btree.c                |  2 +-
 fs/xfs/libxfs/xfs_btree.c                     | 16 +++++-----
 fs/xfs/libxfs/xfs_da_btree.c                  |  6 ++--
 fs/xfs/libxfs/xfs_dir2_block.c                |  6 ++--
 fs/xfs/libxfs/xfs_dir2_data.c                 |  9 +++---
 fs/xfs/libxfs/xfs_dir2_leaf.c                 |  6 ++--
 fs/xfs/libxfs/xfs_dir2_node.c                 |  6 ++--
 fs/xfs/libxfs/xfs_dquot_buf.c                 |  8 ++---
 fs/xfs/libxfs/xfs_ialloc.c                    |  6 ++--
 fs/xfs/libxfs/xfs_ialloc_btree.c              |  2 +-
 fs/xfs/libxfs/xfs_inode_buf.c                 |  2 +-
 fs/xfs/libxfs/xfs_refcount_btree.c            |  2 +-
 fs/xfs/libxfs/xfs_rmap_btree.c                |  2 +-
 fs/xfs/libxfs/xfs_sb.c                        |  4 +--
 fs/xfs/libxfs/xfs_symlink_remote.c            |  6 ++--
 fs/xfs/xfs_attr_inactive.c                    |  2 +-
 fs/xfs/xfs_buf.c                              | 32 +++++++++----------
 fs/xfs/xfs_buf.h                              |  1 +
 fs/xfs/xfs_buf_item.c                         |  4 +--
 fs/xfs/xfs_error.c                            |  2 +-
 fs/xfs/xfs_log_recover.c                      | 11 +++----
 26 files changed, 85 insertions(+), 88 deletions(-)

diff --git a/Documentation/filesystems/xfs-self-describing-metadata.txt b/Documentation/filesystems/xfs-self-describing-metadata.txt
index 68604e67a495..8db0121d0980 100644
--- a/Documentation/filesystems/xfs-self-describing-metadata.txt
+++ b/Documentation/filesystems/xfs-self-describing-metadata.txt
@@ -222,7 +222,7 @@ static void
 xfs_foo_read_verify(
 	struct xfs_buf	*bp)
 {
-       struct xfs_mount *mp = bp->b_target->bt_mount;
+       struct xfs_mount *mp = bp->b_mount;
 
         if ((xfs_sb_version_hascrc(&mp->m_sb) &&
              !xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
@@ -245,7 +245,7 @@ static bool
 xfs_foo_verify(
 	struct xfs_buf		*bp)
 {
-        struct xfs_mount	*mp = bp->b_target->bt_mount;
+        struct xfs_mount	*mp = bp->b_mount;
         struct xfs_ondisk_hdr	*hdr = bp->b_addr;
 
         if (hdr->magic != cpu_to_be32(XFS_FOO_MAGIC))
@@ -272,7 +272,7 @@ static bool
 xfs_foo_verify(
 	struct xfs_buf		*bp)
 {
-        struct xfs_mount	*mp = bp->b_target->bt_mount;
+        struct xfs_mount	*mp = bp->b_mount;
         struct xfs_ondisk_hdr	*hdr = bp->b_addr;
 
         if (hdr->magic == cpu_to_be32(XFS_FOO_CRC_MAGIC)) {
@@ -297,7 +297,7 @@ static void
 xfs_foo_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_fspriv;
 
 	if (!xfs_foo_verify(bp)) {
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index a9ff3cf82cce..88f00beddee7 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -555,7 +555,7 @@ static xfs_failaddr_t
 xfs_agfl_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	struct xfs_agfl	*agfl = XFS_BUF_TO_AGFL(bp);
 	int		i;
 
@@ -596,7 +596,7 @@ static void
 xfs_agfl_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_failaddr_t	fa;
 
 	/*
@@ -621,7 +621,7 @@ static void
 xfs_agfl_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	xfs_failaddr_t		fa;
 
@@ -2586,7 +2586,7 @@ static xfs_failaddr_t
 xfs_agf_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_agf		*agf = XFS_BUF_TO_AGF(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
@@ -2644,7 +2644,7 @@ static void
 xfs_agf_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_failaddr_t	fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -2661,7 +2661,7 @@ static void
 xfs_agf_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	xfs_failaddr_t		fa;
 
diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
index 9fe949f6055e..9b2786ee4081 100644
--- a/fs/xfs/libxfs/xfs_alloc_btree.c
+++ b/fs/xfs/libxfs/xfs_alloc_btree.c
@@ -292,7 +292,7 @@ static xfs_failaddr_t
 xfs_allocbt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_perag	*pag = bp->b_pag;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 1f6e3965ff74..654a599a3754 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -240,7 +240,7 @@ xfs_attr3_leaf_verify(
 	struct xfs_buf			*bp)
 {
 	struct xfs_attr3_icleaf_hdr	ichdr;
-	struct xfs_mount		*mp = bp->b_target->bt_mount;
+	struct xfs_mount		*mp = bp->b_mount;
 	struct xfs_attr_leafblock	*leaf = bp->b_addr;
 	struct xfs_attr_leaf_entry	*entries;
 	uint32_t			end;	/* must be 32bit - see below */
@@ -313,7 +313,7 @@ static void
 xfs_attr3_leaf_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_attr3_leaf_hdr *hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
@@ -343,7 +343,7 @@ static void
 xfs_attr3_leaf_read_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -865,7 +865,7 @@ xfs_attr_shortform_allfit(
 	struct xfs_attr3_icleaf_hdr leafhdr;
 	int			bytes;
 	int			i;
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	leaf = bp->b_addr;
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
@@ -1525,7 +1525,7 @@ xfs_attr_leaf_order(
 {
 	struct xfs_attr3_icleaf_hdr ichdr1;
 	struct xfs_attr3_icleaf_hdr ichdr2;
-	struct xfs_mount *mp = leaf1_bp->b_target->bt_mount;
+	struct xfs_mount *mp = leaf1_bp->b_mount;
 
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr1, leaf1_bp->b_addr);
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr2, leaf2_bp->b_addr);
@@ -2568,7 +2568,7 @@ xfs_attr_leaf_lasthash(
 {
 	struct xfs_attr3_icleaf_hdr ichdr;
 	struct xfs_attr_leaf_entry *entries;
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, bp->b_addr);
 	entries = xfs_attr3_leaf_entryp(bp->b_addr);
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index 65ff600a8067..563c842ddfcf 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -111,7 +111,7 @@ __xfs_attr3_rmt_read_verify(
 	bool		check_crc,
 	xfs_failaddr_t	*failaddr)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	char		*ptr;
 	int		len;
 	xfs_daddr_t	bno;
@@ -175,7 +175,7 @@ static void
 xfs_attr3_rmt_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_failaddr_t	fa;
 	int		blksize = mp->m_attr_geo->blksize;
 	char		*ptr;
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index aff82ed112c9..e6100bd3ec62 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -411,7 +411,7 @@ static xfs_failaddr_t
 xfs_bmbt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	xfs_failaddr_t		fa;
 	unsigned int		level;
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index bbdae2b4559f..a2099c15ac09 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -276,7 +276,7 @@ xfs_btree_lblock_calc_crc(
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 
-	if (!xfs_sb_version_hascrc(&bp->b_target->bt_mount->m_sb))
+	if (!xfs_sb_version_hascrc(&bp->b_mount->m_sb))
 		return;
 	if (bip)
 		block->bb_u.l.bb_lsn = cpu_to_be64(bip->bli_item.li_lsn);
@@ -288,7 +288,7 @@ xfs_btree_lblock_verify_crc(
 	struct xfs_buf		*bp)
 {
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (!xfs_log_check_lsn(mp, be64_to_cpu(block->bb_u.l.bb_lsn)))
@@ -314,7 +314,7 @@ xfs_btree_sblock_calc_crc(
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 
-	if (!xfs_sb_version_hascrc(&bp->b_target->bt_mount->m_sb))
+	if (!xfs_sb_version_hascrc(&bp->b_mount->m_sb))
 		return;
 	if (bip)
 		block->bb_u.s.bb_lsn = cpu_to_be64(bip->bli_item.li_lsn);
@@ -326,7 +326,7 @@ xfs_btree_sblock_verify_crc(
 	struct xfs_buf		*bp)
 {
 	struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (!xfs_log_check_lsn(mp, be64_to_cpu(block->bb_u.s.bb_lsn)))
@@ -4433,7 +4433,7 @@ xfs_btree_lblock_v5hdr_verify(
 	struct xfs_buf		*bp,
 	uint64_t		owner)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
@@ -4454,7 +4454,7 @@ xfs_btree_lblock_verify(
 	struct xfs_buf		*bp,
 	unsigned int		max_recs)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 
 	/* numrecs verification */
@@ -4484,7 +4484,7 @@ xfs_failaddr_t
 xfs_btree_sblock_v5hdr_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_perag	*pag = bp->b_pag;
 
@@ -4510,7 +4510,7 @@ xfs_btree_sblock_verify(
 	struct xfs_buf		*bp,
 	unsigned int		max_recs)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	xfs_agblock_t		agno;
 
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index e2737e2ac2ae..224631d66ade 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -126,7 +126,7 @@ xfs_da3_blkinfo_verify(
 	struct xfs_buf		*bp,
 	struct xfs_da3_blkinfo	*hdr3)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_da_blkinfo	*hdr = &hdr3->hdr;
 
 	if (!xfs_verify_magic16(bp, hdr->magic))
@@ -148,7 +148,7 @@ static xfs_failaddr_t
 xfs_da3_node_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_da_intnode	*hdr = bp->b_addr;
 	struct xfs_da3_icnode_hdr ichdr;
 	const struct xfs_dir_ops *ops;
@@ -186,7 +186,7 @@ static void
 xfs_da3_node_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_da3_node_hdr *hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_dir2_block.c b/fs/xfs/libxfs/xfs_dir2_block.c
index b7d6d78f4ce2..6da84d2631d3 100644
--- a/fs/xfs/libxfs/xfs_dir2_block.c
+++ b/fs/xfs/libxfs/xfs_dir2_block.c
@@ -50,7 +50,7 @@ static xfs_failaddr_t
 xfs_dir3_block_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dir3_blk_hdr	*hdr3 = bp->b_addr;
 
 	if (!xfs_verify_magic(bp, hdr3->magic))
@@ -71,7 +71,7 @@ static void
 xfs_dir3_block_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -88,7 +88,7 @@ static void
 xfs_dir3_block_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_dir3_blk_hdr	*hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index b7b9ce002cb9..17a95b65caf1 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -50,14 +50,13 @@ __xfs_dir3_data_check(
 	int			i;		/* leaf index */
 	int			lastfree;	/* last entry was unused */
 	xfs_dir2_leaf_entry_t	*lep=NULL;	/* block leaf entries */
-	xfs_mount_t		*mp;		/* filesystem mount point */
+	struct xfs_mount	*mp = bp->b_mount;
 	char			*p;		/* current data position */
 	int			stale;		/* count of stale leaves */
 	struct xfs_name		name;
 	const struct xfs_dir_ops *ops;
 	struct xfs_da_geometry	*geo;
 
-	mp = bp->b_target->bt_mount;
 	geo = mp->m_dir_geo;
 
 	/*
@@ -249,7 +248,7 @@ static xfs_failaddr_t
 xfs_dir3_data_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dir3_blk_hdr	*hdr3 = bp->b_addr;
 
 	if (!xfs_verify_magic(bp, hdr3->magic))
@@ -298,7 +297,7 @@ static void
 xfs_dir3_data_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -315,7 +314,7 @@ static void
 xfs_dir3_data_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_dir3_blk_hdr	*hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
index 9c2a0a13ed61..b799c4db2151 100644
--- a/fs/xfs/libxfs/xfs_dir2_leaf.c
+++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
@@ -144,7 +144,7 @@ static xfs_failaddr_t
 xfs_dir3_leaf_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dir2_leaf	*leaf = bp->b_addr;
 	xfs_failaddr_t		fa;
 
@@ -159,7 +159,7 @@ static void
 xfs_dir3_leaf_read_verify(
 	struct xfs_buf  *bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -176,7 +176,7 @@ static void
 xfs_dir3_leaf_write_verify(
 	struct xfs_buf  *bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_dir3_leaf_hdr *hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_dir2_node.c b/fs/xfs/libxfs/xfs_dir2_node.c
index 16731d2d684b..f16139d38208 100644
--- a/fs/xfs/libxfs/xfs_dir2_node.c
+++ b/fs/xfs/libxfs/xfs_dir2_node.c
@@ -84,7 +84,7 @@ static xfs_failaddr_t
 xfs_dir3_free_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dir2_free_hdr *hdr = bp->b_addr;
 
 	if (!xfs_verify_magic(bp, hdr->magic))
@@ -110,7 +110,7 @@ static void
 xfs_dir3_free_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -127,7 +127,7 @@ static void
 xfs_dir3_free_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	struct xfs_dir3_blk_hdr	*hdr3 = bp->b_addr;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_dquot_buf.c b/fs/xfs/libxfs/xfs_dquot_buf.c
index 88fa11071f9f..194d2f0194aa 100644
--- a/fs/xfs/libxfs/xfs_dquot_buf.c
+++ b/fs/xfs/libxfs/xfs_dquot_buf.c
@@ -224,7 +224,7 @@ static xfs_failaddr_t
 xfs_dquot_buf_verify_struct(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	return xfs_dquot_buf_verify(mp, bp, false);
 }
@@ -233,7 +233,7 @@ static void
 xfs_dquot_buf_read_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	if (!xfs_dquot_buf_verify_crc(mp, bp, false))
 		return;
@@ -250,7 +250,7 @@ static void
 xfs_dquot_buf_readahead_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	if (!xfs_dquot_buf_verify_crc(mp, bp, true) ||
 	    xfs_dquot_buf_verify(mp, bp, true) != NULL) {
@@ -268,7 +268,7 @@ static void
 xfs_dquot_buf_write_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	xfs_dquot_buf_verify(mp, bp, false);
 }
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index fe9898875097..76f9c5182d74 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -2493,7 +2493,7 @@ static xfs_failaddr_t
 xfs_agi_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	struct xfs_agi	*agi = XFS_BUF_TO_AGI(bp);
 	int		i;
 
@@ -2545,7 +2545,7 @@ static void
 xfs_agi_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_failaddr_t	fa;
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
@@ -2562,7 +2562,7 @@ static void
 xfs_agi_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	xfs_failaddr_t		fa;
 
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index bc2dfacd2f4a..16f7a001b29c 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -255,7 +255,7 @@ static xfs_failaddr_t
 xfs_inobt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	xfs_failaddr_t		fa;
 	unsigned int		level;
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index e021d5133ccb..c5c11c79f979 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -80,7 +80,7 @@ xfs_inode_buf_verify(
 	struct xfs_buf	*bp,
 	bool		readahead)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_agnumber_t	agno;
 	int		i;
 	int		ni;
diff --git a/fs/xfs/libxfs/xfs_refcount_btree.c b/fs/xfs/libxfs/xfs_refcount_btree.c
index 5d9de9b21726..5d1dfc49ac89 100644
--- a/fs/xfs/libxfs/xfs_refcount_btree.c
+++ b/fs/xfs/libxfs/xfs_refcount_btree.c
@@ -203,7 +203,7 @@ STATIC xfs_failaddr_t
 xfs_refcountbt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_perag	*pag = bp->b_pag;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index 5d1f8884c888..e9fe53e0dcc8 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -292,7 +292,7 @@ static xfs_failaddr_t
 xfs_rmapbt_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 	struct xfs_perag	*pag = bp->b_pag;
 	xfs_failaddr_t		fa;
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index e76a3e5d28d7..5fd629244aee 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -686,7 +686,7 @@ xfs_sb_read_verify(
 	struct xfs_buf		*bp)
 {
 	struct xfs_sb		sb;
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dsb		*dsb = XFS_BUF_TO_SBP(bp);
 	int			error;
 
@@ -752,7 +752,7 @@ xfs_sb_write_verify(
 	struct xfs_buf		*bp)
 {
 	struct xfs_sb		sb;
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	int			error;
 
diff --git a/fs/xfs/libxfs/xfs_symlink_remote.c b/fs/xfs/libxfs/xfs_symlink_remote.c
index a0ccc253c43d..264b94bb2295 100644
--- a/fs/xfs/libxfs/xfs_symlink_remote.c
+++ b/fs/xfs/libxfs/xfs_symlink_remote.c
@@ -90,7 +90,7 @@ static xfs_failaddr_t
 xfs_symlink_verify(
 	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
 
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
@@ -116,7 +116,7 @@ static void
 xfs_symlink_read_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	xfs_failaddr_t	fa;
 
 	/* no verification of non-crc buffers */
@@ -136,7 +136,7 @@ static void
 xfs_symlink_write_verify(
 	struct xfs_buf	*bp)
 {
-	struct xfs_mount *mp = bp->b_target->bt_mount;
+	struct xfs_mount *mp = bp->b_mount;
 	struct xfs_buf_log_item	*bip = bp->b_log_item;
 	xfs_failaddr_t		fa;
 
diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
index 228821b2ebe0..d4f4c96bcd4c 100644
--- a/fs/xfs/xfs_attr_inactive.c
+++ b/fs/xfs/xfs_attr_inactive.c
@@ -121,7 +121,7 @@ xfs_attr3_leaf_inactive(
 	int			size;
 	int			tmp;
 	int			i;
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 
 	leaf = bp->b_addr;
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 26027a93bdd3..9477702d60a2 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -243,6 +243,7 @@ _xfs_buf_alloc(
 	sema_init(&bp->b_sema, 0); /* held, no waiters */
 	spin_lock_init(&bp->b_lock);
 	bp->b_target = target;
+	bp->b_mount = target->bt_mount;
 	bp->b_flags = flags;
 
 	/*
@@ -267,7 +268,7 @@ _xfs_buf_alloc(
 	atomic_set(&bp->b_pin_count, 0);
 	init_waitqueue_head(&bp->b_waiters);
 
-	XFS_STATS_INC(target->bt_mount, xb_create);
+	XFS_STATS_INC(bp->b_mount, xb_create);
 	trace_xfs_buf_init(bp, _RET_IP_);
 
 	return bp;
@@ -424,12 +425,12 @@ xfs_buf_allocate_memory(
 					current->comm, current->pid,
 					__func__, gfp_mask);
 
-			XFS_STATS_INC(bp->b_target->bt_mount, xb_page_retries);
+			XFS_STATS_INC(bp->b_mount, xb_page_retries);
 			congestion_wait(BLK_RW_ASYNC, HZ/50);
 			goto retry;
 		}
 
-		XFS_STATS_INC(bp->b_target->bt_mount, xb_page_found);
+		XFS_STATS_INC(bp->b_mount, xb_page_found);
 
 		nbytes = min_t(size_t, size, PAGE_SIZE - offset);
 		size -= nbytes;
@@ -1102,7 +1103,7 @@ xfs_buf_lock(
 	trace_xfs_buf_lock(bp, _RET_IP_);
 
 	if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
-		xfs_log_force(bp->b_target->bt_mount, 0);
+		xfs_log_force(bp->b_mount, 0);
 	down(&bp->b_sema);
 
 	trace_xfs_buf_lock_done(bp, _RET_IP_);
@@ -1191,7 +1192,7 @@ xfs_buf_ioend_async(
 	struct xfs_buf	*bp)
 {
 	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
-	queue_work(bp->b_target->bt_mount->m_buf_workqueue, &bp->b_ioend_work);
+	queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
 }
 
 void
@@ -1210,7 +1211,7 @@ xfs_buf_ioerror_alert(
 	struct xfs_buf		*bp,
 	const char		*func)
 {
-	xfs_alert(bp->b_target->bt_mount,
+	xfs_alert(bp->b_mount,
 "metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
 			func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
 			-bp->b_error);
@@ -1229,10 +1230,8 @@ xfs_bwrite(
 			 XBF_WRITE_FAIL | XBF_DONE);
 
 	error = xfs_buf_submit(bp);
-	if (error) {
-		xfs_force_shutdown(bp->b_target->bt_mount,
-				   SHUTDOWN_META_IO_ERROR);
-	}
+	if (error)
+		xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
 	return error;
 }
 
@@ -1369,12 +1368,12 @@ _xfs_buf_ioapply(
 		if (bp->b_ops) {
 			bp->b_ops->verify_write(bp);
 			if (bp->b_error) {
-				xfs_force_shutdown(bp->b_target->bt_mount,
+				xfs_force_shutdown(bp->b_mount,
 						   SHUTDOWN_CORRUPT_INCORE);
 				return;
 			}
 		} else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
-			struct xfs_mount *mp = bp->b_target->bt_mount;
+			struct xfs_mount *mp = bp->b_mount;
 
 			/*
 			 * non-crc filesystems don't attach verifiers during
@@ -1452,7 +1451,7 @@ __xfs_buf_submit(
 	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
 
 	/* on shutdown we stale and complete the buffer immediately */
-	if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
+	if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
 		xfs_buf_ioerror(bp, -EIO);
 		bp->b_flags &= ~XBF_DONE;
 		xfs_buf_stale(bp);
@@ -2107,8 +2106,7 @@ void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 	 * This allows userspace to disrupt buffer caching for debug/testing
 	 * purposes.
 	 */
-	if (XFS_TEST_ERROR(false, bp->b_target->bt_mount,
-			   XFS_ERRTAG_BUF_LRU_REF))
+	if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
 		lru_ref = 0;
 
 	atomic_set(&bp->b_lru_ref, lru_ref);
@@ -2124,7 +2122,7 @@ xfs_verify_magic(
 	struct xfs_buf		*bp,
 	__be32			dmagic)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	int			idx;
 
 	idx = xfs_sb_version_hascrc(&mp->m_sb);
@@ -2142,7 +2140,7 @@ xfs_verify_magic16(
 	struct xfs_buf		*bp,
 	__be16			dmagic)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	int			idx;
 
 	idx = xfs_sb_version_hascrc(&mp->m_sb);
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index f95cf810126e..284e9955a7a5 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -151,6 +151,7 @@ typedef struct xfs_buf {
 	wait_queue_head_t	b_waiters;	/* unpin waiters */
 	struct list_head	b_list;
 	struct xfs_perag	*b_pag;		/* contains rbtree root */
+	struct xfs_mount	*b_mount;
 	xfs_buftarg_t		*b_target;	/* buffer target (device) */
 	void			*b_addr;	/* virtual address of buffer */
 	struct work_struct	b_ioend_work;
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 65b32acfa0f6..f3d814dc7518 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -520,7 +520,7 @@ xfs_buf_item_push(
 	/* has a previous flush failed due to IO errors? */
 	if ((bp->b_flags & XBF_WRITE_FAIL) &&
 	    ___ratelimit(&xfs_buf_write_fail_rl_state, "XFS: Failing async write")) {
-		xfs_warn(bp->b_target->bt_mount,
+		xfs_warn(bp->b_mount,
 "Failing async write on buffer block 0x%llx. Retrying async write.",
 			 (long long)bp->b_bn);
 	}
@@ -743,7 +743,7 @@ xfs_buf_item_init(
 	 * this buffer. If we do already have one, there is
 	 * nothing to do here so return.
 	 */
-	ASSERT(bp->b_target->bt_mount == mp);
+	ASSERT(bp->b_mount == mp);
 	if (bip) {
 		ASSERT(bip->bli_item.li_type == XFS_LI_BUF);
 		ASSERT(!bp->b_transp);
diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index a1e177f66404..9a51a7b80fed 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -353,7 +353,7 @@ xfs_buf_verifier_error(
 	size_t			bufsz,
 	xfs_failaddr_t		failaddr)
 {
-	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_mount	*mp = bp->b_mount;
 	xfs_failaddr_t		fa;
 	int			sz;
 
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index bbe5e38e2932..b03921b0548a 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -299,10 +299,9 @@ xlog_recover_iodone(
 		 * We're not going to bother about retrying
 		 * this during recovery. One strike!
 		 */
-		if (!XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
+		if (!XFS_FORCED_SHUTDOWN(bp->b_mount)) {
 			xfs_buf_ioerror_alert(bp, __func__);
-			xfs_force_shutdown(bp->b_target->bt_mount,
-						SHUTDOWN_META_IO_ERROR);
+			xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
 		}
 	}
 
@@ -2821,7 +2820,7 @@ xlog_recover_buffer_pass2(
 		xfs_buf_stale(bp);
 		error = xfs_bwrite(bp);
 	} else {
-		ASSERT(bp->b_target->bt_mount == mp);
+		ASSERT(bp->b_mount == mp);
 		bp->b_iodone = xlog_recover_iodone;
 		xfs_buf_delwri_queue(bp, buffer_list);
 	}
@@ -3183,7 +3182,7 @@ xlog_recover_inode_pass2(
 	/* re-generate the checksum. */
 	xfs_dinode_calc_crc(log->l_mp, dip);
 
-	ASSERT(bp->b_target->bt_mount == mp);
+	ASSERT(bp->b_mount == mp);
 	bp->b_iodone = xlog_recover_iodone;
 	xfs_buf_delwri_queue(bp, buffer_list);
 
@@ -3322,7 +3321,7 @@ xlog_recover_dquot_pass2(
 	}
 
 	ASSERT(dq_f->qlf_size == 2);
-	ASSERT(bp->b_target->bt_mount == mp);
+	ASSERT(bp->b_mount == mp);
 	bp->b_iodone = xlog_recover_iodone;
 	xfs_buf_delwri_queue(bp, buffer_list);
 
-- 
2.20.1

Re: use bios directly in the log code v4

[Darrick J. Wong]

On Wed, Jun 05, 2019 at 09:14:47PM +0200, Christoph Hellwig wrote:
> Hi all,
> 
> this series switches the log writing and log recovery code to use bios
> directly, and remove various special cases from the buffer cache code.
> 
> A git tree is available here:
> 
>     git://git.infradead.org/users/hch/xfs.git xfs-log-bio
> 
> Gitweb:
> 
>     http://git.infradead.org/users/hch/xfs.git/shortlog/refs/heads/xfs-log-bio

I don't know if either (a) I'll find something in the other log cleanup
series to comment on or (b) if Dave has any further thoughts about
whatever it is he's doing with xfs_buf in userspace.  However, for
patches 1-15 and 17-24, I think this looks good enough for more
widespread testing, so...

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> 
> Chances since v3:
>  - add a few additional cleanup patches
>  - clean up iclog allocation
>  - drop a not required vmap invalidation
>  - better document the iclog size fields
>  - fix vmap invalidation
> 
> Changes since v2:
>  - rename the 'flush' flag to 'need_flush'
>  - spelling fixes
>  - minor cleanups
> 
> Changes since v1:
>  - rebased to not required the log item series first
>  - split the bio-related code out of xfs_log_recover.c into a new file
>    to ease using xfs_log_recover.c in xfsprogs
>  - use kmem_alloc_large instead of vmalloc to allocate the buffer
>  - additional minor cleanups