From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
hch@lst.de, david@fromorbit.com,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 1/6] iomap: Use a IOMAP_COW/srcmap for a read-modify-write I/O
Date: Fri, 21 Jun 2019 17:46:24 -0700 [thread overview]
Message-ID: <20190622004624.GC1611011@magnolia> (raw)
In-Reply-To: <20190621192828.28900-2-rgoldwyn@suse.de>
On Fri, Jun 21, 2019 at 02:28:23PM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
>
> Introduces a new type IOMAP_COW, which means the data at offset
> must be read from a srcmap and copied before performing the
> write on the offset.
>
> The srcmap is used to identify where the read is to be performed
> from. This is passed to iomap->begin(), which is supposed to
> put in the details for reading, typically set with type IOMAP_READ.
What is IOMAP_READ ?
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
> fs/dax.c | 8 +++++---
> fs/ext2/inode.c | 2 +-
> fs/ext4/inode.c | 2 +-
> fs/gfs2/bmap.c | 3 ++-
> fs/internal.h | 2 +-
> fs/iomap.c | 31 ++++++++++++++++---------------
> fs/xfs/xfs_iomap.c | 9 ++++++---
> include/linux/iomap.h | 4 +++-
> 8 files changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 2e48c7ebb973..80b9e2599223 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1078,7 +1078,7 @@ EXPORT_SYMBOL_GPL(__dax_zero_page_range);
>
> static loff_t
> dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> - struct iomap *iomap)
> + struct iomap *iomap, struct iomap *srcmap)
> {
> struct block_device *bdev = iomap->bdev;
> struct dax_device *dax_dev = iomap->dax_dev;
> @@ -1236,6 +1236,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> unsigned long vaddr = vmf->address;
> loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
> struct iomap iomap = { 0 };
> + struct iomap srcmap = { 0 };
> unsigned flags = IOMAP_FAULT;
> int error, major = 0;
> bool write = vmf->flags & FAULT_FLAG_WRITE;
> @@ -1280,7 +1281,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> * the file system block size to be equal the page size, which means
> * that we never have to deal with more than a single extent here.
> */
> - error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
> + error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap, &srcmap);
> if (iomap_errp)
> *iomap_errp = error;
> if (error) {
> @@ -1460,6 +1461,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> struct inode *inode = mapping->host;
> vm_fault_t result = VM_FAULT_FALLBACK;
> struct iomap iomap = { 0 };
> + struct iomap srcmap = { 0 };
> pgoff_t max_pgoff;
> void *entry;
> loff_t pos;
> @@ -1534,7 +1536,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> * to look up our filesystem block.
> */
> pos = (loff_t)xas.xa_index << PAGE_SHIFT;
> - error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
> + error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap, &srcmap);
Line too long?
Also, I guess the DAX and directio write paths will just WARN_ON_ONCE if
someone feeds them an IOMAP_COW type iomap?
Ah, right, I guess the only filesystems that use iomap directio and
iomap dax don't support COW. :)
--D
> if (error)
> goto unlock_entry;
>
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index e474127dd255..f081f11980ad 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -801,7 +801,7 @@ int ext2_get_block(struct inode *inode, sector_t iblock,
>
> #ifdef CONFIG_FS_DAX
> static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> - unsigned flags, struct iomap *iomap)
> + unsigned flags, struct iomap *iomap, struct iomap *srcmap)
> {
> unsigned int blkbits = inode->i_blkbits;
> unsigned long first_block = offset >> blkbits;
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c7f77c643008..a8017e0c302b 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3437,7 +3437,7 @@ static bool ext4_inode_datasync_dirty(struct inode *inode)
> }
>
> static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> - unsigned flags, struct iomap *iomap)
> + unsigned flags, struct iomap *iomap, struct iomap *srcmap)
> {
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> unsigned int blkbits = inode->i_blkbits;
> diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
> index 93ea1d529aa3..affa0c4305b7 100644
> --- a/fs/gfs2/bmap.c
> +++ b/fs/gfs2/bmap.c
> @@ -1124,7 +1124,8 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
> }
>
> static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
> - unsigned flags, struct iomap *iomap)
> + unsigned flags, struct iomap *iomap,
> + struct iomap *srcmap)
> {
> struct gfs2_inode *ip = GFS2_I(inode);
> struct metapath mp = { .mp_aheight = 1, };
> diff --git a/fs/internal.h b/fs/internal.h
> index a48ef81be37d..79e495d86165 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -188,7 +188,7 @@ extern int do_vfs_ioctl(struct file *file, unsigned int fd, unsigned int cmd,
> * iomap support:
> */
> typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
> - void *data, struct iomap *iomap);
> + void *data, struct iomap *iomap, struct iomap *srcmap);
>
> loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
> unsigned flags, const struct iomap_ops *ops, void *data,
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 23ef63fd1669..6648957af268 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -41,6 +41,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
> const struct iomap_ops *ops, void *data, iomap_actor_t actor)
> {
> struct iomap iomap = { 0 };
> + struct iomap srcmap = { 0 };
> loff_t written = 0, ret;
>
> /*
> @@ -55,7 +56,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
> * expose transient stale data. If the reserve fails, we can safely
> * back out at this point as there is nothing to undo.
> */
> - ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
> + ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
> if (ret)
> return ret;
> if (WARN_ON(iomap.offset > pos))
> @@ -75,7 +76,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
> * we can do the copy-in page by page without having to worry about
> * failures exposing transient data.
> */
> - written = actor(inode, pos, length, data, &iomap);
> + written = actor(inode, pos, length, data, &iomap, &srcmap);
>
> /*
> * Now the data has been copied, commit the range we've copied. This
> @@ -282,7 +283,7 @@ iomap_read_inline_data(struct inode *inode, struct page *page,
>
> static loff_t
> iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> - struct iomap *iomap)
> + struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_readpage_ctx *ctx = data;
> struct page *page = ctx->cur_page;
> @@ -424,7 +425,7 @@ iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
>
> static loff_t
> iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_readpage_ctx *ctx = data;
> loff_t done, ret;
> @@ -444,7 +445,7 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
> ctx->cur_page_in_bio = false;
> }
> ret = iomap_readpage_actor(inode, pos + done, length - done,
> - ctx, iomap);
> + ctx, iomap, srcmap);
> }
>
> return done;
> @@ -796,7 +797,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
>
> static loff_t
> iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> - struct iomap *iomap)
> + struct iomap *iomap, struct iomap *srcmap)
> {
> struct iov_iter *i = data;
> long status = 0;
> @@ -913,7 +914,7 @@ __iomap_read_page(struct inode *inode, loff_t offset)
>
> static loff_t
> iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> - struct iomap *iomap)
> + struct iomap *iomap, struct iomap *srcmap)
> {
> long status = 0;
> ssize_t written = 0;
> @@ -1002,7 +1003,7 @@ static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
>
> static loff_t
> iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> bool *did_zero = data;
> loff_t written = 0;
> @@ -1071,7 +1072,7 @@ EXPORT_SYMBOL_GPL(iomap_truncate_page);
>
> static loff_t
> iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> struct page *page = data;
> int ret;
> @@ -1169,7 +1170,7 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
>
> static loff_t
> iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> - struct iomap *iomap)
> + struct iomap *iomap, struct iomap *srcmap)
> {
> struct fiemap_ctx *ctx = data;
> loff_t ret = length;
> @@ -1343,7 +1344,7 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
>
> static loff_t
> iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> switch (iomap->type) {
> case IOMAP_UNWRITTEN:
> @@ -1389,7 +1390,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_hole);
>
> static loff_t
> iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> switch (iomap->type) {
> case IOMAP_HOLE:
> @@ -1790,7 +1791,7 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
>
> static loff_t
> iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_dio *dio = data;
>
> @@ -2057,7 +2058,7 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
> * distinction between written and unwritten extents.
> */
> static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
> - loff_t count, void *data, struct iomap *iomap)
> + loff_t count, void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_swapfile_info *isi = data;
> int error;
> @@ -2161,7 +2162,7 @@ EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
>
> static loff_t
> iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
> - void *data, struct iomap *iomap)
> + void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> sector_t *bno = data, addr;
>
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 63d323916bba..6116a75f03da 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -925,7 +925,8 @@ xfs_file_iomap_begin(
> loff_t offset,
> loff_t length,
> unsigned flags,
> - struct iomap *iomap)
> + struct iomap *iomap,
> + struct iomap *srcmap)
> {
> struct xfs_inode *ip = XFS_I(inode);
> struct xfs_mount *mp = ip->i_mount;
> @@ -1148,7 +1149,8 @@ xfs_seek_iomap_begin(
> loff_t offset,
> loff_t length,
> unsigned flags,
> - struct iomap *iomap)
> + struct iomap *iomap,
> + struct iomap *srcmap)
> {
> struct xfs_inode *ip = XFS_I(inode);
> struct xfs_mount *mp = ip->i_mount;
> @@ -1234,7 +1236,8 @@ xfs_xattr_iomap_begin(
> loff_t offset,
> loff_t length,
> unsigned flags,
> - struct iomap *iomap)
> + struct iomap *iomap,
> + struct iomap *srcmap)
> {
> struct xfs_inode *ip = XFS_I(inode);
> struct xfs_mount *mp = ip->i_mount;
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 2103b94cb1bf..f49767c7fd83 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -25,6 +25,7 @@ struct vm_fault;
> #define IOMAP_MAPPED 0x03 /* blocks allocated at @addr */
> #define IOMAP_UNWRITTEN 0x04 /* blocks allocated at @addr in unwritten state */
> #define IOMAP_INLINE 0x05 /* data inline in the inode */
> +#define IOMAP_COW 0x06 /* copy data from srcmap before writing */
>
> /*
> * Flags for all iomap mappings:
> @@ -102,7 +103,8 @@ struct iomap_ops {
> * The actual length is returned in iomap->length.
> */
> int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length,
> - unsigned flags, struct iomap *iomap);
> + unsigned flags, struct iomap *iomap,
> + struct iomap *srcmap);
>
> /*
> * Commit and/or unreserve space previous allocated using iomap_begin.
> --
> 2.16.4
>
next prev parent reply other threads:[~2019-06-22 0:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-21 19:28 [PATCH 0/6] Btrfs iomap Goldwyn Rodrigues
2019-06-21 19:28 ` [PATCH 1/6] iomap: Use a IOMAP_COW/srcmap for a read-modify-write I/O Goldwyn Rodrigues
2019-06-22 0:46 ` Darrick J. Wong [this message]
2019-06-25 19:17 ` Goldwyn Rodrigues
2019-06-26 6:21 ` Christoph Hellwig
2019-06-24 7:07 ` Christoph Hellwig
2019-06-25 19:14 ` Goldwyn Rodrigues
2019-06-26 1:36 ` Shiyang Ruan
2019-06-26 6:39 ` Christoph Hellwig
2019-06-26 16:10 ` Goldwyn Rodrigues
2019-06-26 17:34 ` Darrick J. Wong
2019-06-26 18:00 ` Darrick J. Wong
2019-06-26 18:42 ` Goldwyn Rodrigues
2019-06-21 19:28 ` [PATCH 2/6] iomap: Read page from srcmap for IOMAP_COW Goldwyn Rodrigues
2019-06-22 0:41 ` Darrick J. Wong
2019-06-21 19:28 ` [PATCH 3/6] iomap: Check iblocksize before transforming page->private Goldwyn Rodrigues
2019-06-22 0:21 ` Darrick J. Wong
2019-06-25 19:22 ` Goldwyn Rodrigues
2019-06-24 7:05 ` Christoph Hellwig
2019-06-25 18:56 ` Goldwyn Rodrigues
2019-06-25 20:04 ` Filipe Manana
2019-06-26 3:03 ` Goldwyn Rodrigues
2019-06-26 6:42 ` Nikolay Borisov
2019-06-26 6:16 ` Christoph Hellwig
2019-06-21 19:28 ` [PATCH 4/6] btrfs: Add a simple buffered iomap write Goldwyn Rodrigues
2019-06-21 19:28 ` [PATCH 5/6] btrfs: Add CoW in iomap based writes Goldwyn Rodrigues
2019-06-21 19:28 ` [PATCH 6/6] btrfs: remove buffered write code made unnecessary Goldwyn Rodrigues
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