fix a DEBUG-only assert failure in xfs/538 v2

fix a DEBUG-only assert failure in xfs/538 v2

[Christoph Hellwig]

Hi all,

when testing with very small rtgroups I've seen relatively frequent
failures in xfs/538 where an assert about the da block type triggers
that should be entirely impossible to trigger by the expected code
flow.

It turns out for this two things had to come together:  a bug in the
attr code to uses ENOSPC to signal a condition that is not related
to run out free blocks, but which can also be triggered when we
actually run out of free blocks, and a debug in the DEBUG only
xfs_bmap_exact_minlen_extent_alloc allocator trigger only by the
specific error injection used in this and a few other tests.

This series tries to fix both issues and clean up the surrounding
code a bit to make it more obvious.

Changes since v1:
 - fix build for !DEBUG builds
 - improve a comment
 - fix a comment typo

Diffstat;
 xfs_attr.c      |  178 ++++++++++++++++++++++----------------------------------
 xfs_attr_leaf.c |   40 ++++++------
 xfs_attr_leaf.h |    2 
 xfs_bmap.c      |  134 +++++++++++++-----------------------------
 xfs_da_btree.c  |    5 -
 5 files changed, 143 insertions(+), 216 deletions(-)

[PATCH 1/6] xfs: merge xfs_attr_leaf_try_add into xfs_attr_leaf_addname

[Christoph Hellwig]

xfs_attr_leaf_try_add is only called by xfs_attr_leaf_addname, and
merging the two will simplify a following error handling fix.

To facilitate this move the remote block state save/restore helpers up in
the file so that they don't need forward declarations now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_attr.c | 176 ++++++++++++++++-----------------------
 1 file changed, 74 insertions(+), 102 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index f30bcc64100d56..b9df7a6b1f9d61 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -51,7 +51,6 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
 STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
 STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
 STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
-STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args);
 
 /*
  * Internal routines when attribute list is more than one block.
@@ -437,6 +436,33 @@ xfs_attr_hashval(
 	return xfs_attr_hashname(name, namelen);
 }
 
+/* Save the current remote block info and clear the current pointers. */
+static void
+xfs_attr_save_rmt_blk(
+	struct xfs_da_args	*args)
+{
+	args->blkno2 = args->blkno;
+	args->index2 = args->index;
+	args->rmtblkno2 = args->rmtblkno;
+	args->rmtblkcnt2 = args->rmtblkcnt;
+	args->rmtvaluelen2 = args->rmtvaluelen;
+	args->rmtblkno = 0;
+	args->rmtblkcnt = 0;
+	args->rmtvaluelen = 0;
+}
+
+/* Set stored info about a remote block */
+static void
+xfs_attr_restore_rmt_blk(
+	struct xfs_da_args	*args)
+{
+	args->blkno = args->blkno2;
+	args->index = args->index2;
+	args->rmtblkno = args->rmtblkno2;
+	args->rmtblkcnt = args->rmtblkcnt2;
+	args->rmtvaluelen = args->rmtvaluelen2;
+}
+
 /*
  * PPTR_REPLACE operations require the caller to set the old and new names and
  * values explicitly.  Update the canonical fields to the new name and value
@@ -482,49 +508,77 @@ xfs_attr_complete_op(
 	return replace_state;
 }
 
+/*
+ * Try to add an attribute to an inode in leaf form.
+ */
 static int
 xfs_attr_leaf_addname(
 	struct xfs_attr_intent	*attr)
 {
 	struct xfs_da_args	*args = attr->xattri_da_args;
+	struct xfs_buf		*bp;
 	int			error;
 
 	ASSERT(xfs_attr_is_leaf(args->dp));
 
+	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 0, &bp);
+	if (error)
+		return error;
+
 	/*
-	 * Use the leaf buffer we may already hold locked as a result of
-	 * a sf-to-leaf conversion.
+	 * Look up the xattr name to set the insertion point for the new xattr.
 	 */
-	error = xfs_attr_leaf_try_add(args);
-
-	if (error == -ENOSPC) {
-		error = xfs_attr3_leaf_to_node(args);
-		if (error)
-			return error;
+	error = xfs_attr3_leaf_lookup_int(bp, args);
+	switch (error) {
+	case -ENOATTR:
+		if (args->op_flags & XFS_DA_OP_REPLACE)
+			goto out_brelse;
+		break;
+	case -EEXIST:
+		if (!(args->op_flags & XFS_DA_OP_REPLACE))
+			goto out_brelse;
 
+		trace_xfs_attr_leaf_replace(args);
 		/*
-		 * We're not in leaf format anymore, so roll the transaction and
-		 * retry the add to the newly allocated node block.
+		 * Save the existing remote attr state so that the current
+		 * values reflect the state of the new attribute we are about to
+		 * add, not the attribute we just found and will remove later.
 		 */
-		attr->xattri_dela_state = XFS_DAS_NODE_ADD;
-		goto out;
+		xfs_attr_save_rmt_blk(args);
+		break;
+	case 0:
+		break;
+	default:
+		goto out_brelse;
 	}
-	if (error)
-		return error;
 
 	/*
 	 * We need to commit and roll if we need to allocate remote xattr blocks
 	 * or perform more xattr manipulations. Otherwise there is nothing more
 	 * to do and we can return success.
 	 */
-	if (args->rmtblkno)
+	error = xfs_attr3_leaf_add(bp, args);
+	if (error) {
+		if (error != -ENOSPC)
+			return error;
+		error = xfs_attr3_leaf_to_node(args);
+		if (error)
+			return error;
+
+		attr->xattri_dela_state = XFS_DAS_NODE_ADD;
+	} else if (args->rmtblkno) {
 		attr->xattri_dela_state = XFS_DAS_LEAF_SET_RMT;
-	else
-		attr->xattri_dela_state = xfs_attr_complete_op(attr,
-							XFS_DAS_LEAF_REPLACE);
-out:
+	} else {
+		attr->xattri_dela_state =
+			xfs_attr_complete_op(attr, XFS_DAS_LEAF_REPLACE);
+	}
+
 	trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state, args->dp);
 	return error;
+
+out_brelse:
+	xfs_trans_brelse(args->trans, bp);
+	return error;
 }
 
 /*
@@ -1170,88 +1224,6 @@ xfs_attr_shortform_addname(
  * External routines when attribute list is one block
  *========================================================================*/
 
-/* Save the current remote block info and clear the current pointers. */
-static void
-xfs_attr_save_rmt_blk(
-	struct xfs_da_args	*args)
-{
-	args->blkno2 = args->blkno;
-	args->index2 = args->index;
-	args->rmtblkno2 = args->rmtblkno;
-	args->rmtblkcnt2 = args->rmtblkcnt;
-	args->rmtvaluelen2 = args->rmtvaluelen;
-	args->rmtblkno = 0;
-	args->rmtblkcnt = 0;
-	args->rmtvaluelen = 0;
-}
-
-/* Set stored info about a remote block */
-static void
-xfs_attr_restore_rmt_blk(
-	struct xfs_da_args	*args)
-{
-	args->blkno = args->blkno2;
-	args->index = args->index2;
-	args->rmtblkno = args->rmtblkno2;
-	args->rmtblkcnt = args->rmtblkcnt2;
-	args->rmtvaluelen = args->rmtvaluelen2;
-}
-
-/*
- * Tries to add an attribute to an inode in leaf form
- *
- * This function is meant to execute as part of a delayed operation and leaves
- * the transaction handling to the caller.  On success the attribute is added
- * and the inode and transaction are left dirty.  If there is not enough space,
- * the attr data is converted to node format and -ENOSPC is returned. Caller is
- * responsible for handling the dirty inode and transaction or adding the attr
- * in node format.
- */
-STATIC int
-xfs_attr_leaf_try_add(
-	struct xfs_da_args	*args)
-{
-	struct xfs_buf		*bp;
-	int			error;
-
-	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 0, &bp);
-	if (error)
-		return error;
-
-	/*
-	 * Look up the xattr name to set the insertion point for the new xattr.
-	 */
-	error = xfs_attr3_leaf_lookup_int(bp, args);
-	switch (error) {
-	case -ENOATTR:
-		if (args->op_flags & XFS_DA_OP_REPLACE)
-			goto out_brelse;
-		break;
-	case -EEXIST:
-		if (!(args->op_flags & XFS_DA_OP_REPLACE))
-			goto out_brelse;
-
-		trace_xfs_attr_leaf_replace(args);
-		/*
-		 * Save the existing remote attr state so that the current
-		 * values reflect the state of the new attribute we are about to
-		 * add, not the attribute we just found and will remove later.
-		 */
-		xfs_attr_save_rmt_blk(args);
-		break;
-	case 0:
-		break;
-	default:
-		goto out_brelse;
-	}
-
-	return xfs_attr3_leaf_add(bp, args);
-
-out_brelse:
-	xfs_trans_brelse(args->trans, bp);
-	return error;
-}
-
 /*
  * Return EEXIST if attr is found, or ENOATTR if not
  */
-- 
2.43.0

Re: [PATCH 1/6] xfs: merge xfs_attr_leaf_try_add into xfs_attr_leaf_addname

[Chandan Babu R]

On Sat, Aug 24, 2024 at 05:40:07 AM +0200, Christoph Hellwig wrote:
> xfs_attr_leaf_try_add is only called by xfs_attr_leaf_addname, and
> merging the two will simplify a following error handling fix.
>
> To facilitate this move the remote block state save/restore helpers up in
> the file so that they don't need forward declarations now.
>

Hi,

This patch causes generic/449 to execute indefinitely when using the following
fstest configuration,

TEST_DEV=/dev/loop16
SCRATCH_DEV_POOL="/dev/loop5 /dev/loop6 /dev/loop7 /dev/loop8 /dev/loop9 /dev/loop10 /dev/loop11 /dev/loop12"
MKFS_OPTIONS='-f -m reflink=1,rmapbt=1, -i sparse=1, -b size=1024,'
MOUNT_OPTIONS='-o usrquota,grpquota,prjquota'
TEST_FS_MOUNT_OPTS="$TEST_FS_MOUNT_OPTS -o usrquota,grpquota,prjquota"
USE_EXTERNAL=no
LOGWRITES_DEV=/dev/loop15

Can you please check this?

-- 
Chandan

Re: [PATCH 1/6] xfs: merge xfs_attr_leaf_try_add into xfs_attr_leaf_addname

[Christoph Hellwig]

On Mon, Sep 02, 2024 at 12:08:41PM +0530, Chandan Babu R wrote:
> On Sat, Aug 24, 2024 at 05:40:07 AM +0200, Christoph Hellwig wrote:
> > xfs_attr_leaf_try_add is only called by xfs_attr_leaf_addname, and
> > merging the two will simplify a following error handling fix.
> >
> > To facilitate this move the remote block state save/restore helpers up in
> > the file so that they don't need forward declarations now.
> >
> 
> Hi,
> 
> This patch causes generic/449 to execute indefinitely when using the following
> fstest configuration,

FYI, the culprit actually was the following patch in the series, but
I've reproduced and fixed it yesterday and am about to send a fixed
up series.

[PATCH 2/6] xfs: return bool from xfs_attr3_leaf_add

[Christoph Hellwig]

xfs_attr3_leaf_add only has two potential return values, indicating if the
entry could be added or not.  Replace the errno return with a bool so that
ENOSPC from it can't easily be confused with a real ENOSPC.

Remove the return value from the xfs_attr3_leaf_add_work helper entirely,
as it always return 0.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_attr.c      | 12 ++++--------
 fs/xfs/libxfs/xfs_attr_leaf.c | 37 ++++++++++++++++++-----------------
 fs/xfs/libxfs/xfs_attr_leaf.h |  2 +-
 3 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index b9df7a6b1f9d61..c3ddea016eac95 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -557,10 +557,7 @@ xfs_attr_leaf_addname(
 	 * or perform more xattr manipulations. Otherwise there is nothing more
 	 * to do and we can return success.
 	 */
-	error = xfs_attr3_leaf_add(bp, args);
-	if (error) {
-		if (error != -ENOSPC)
-			return error;
+	if (!xfs_attr3_leaf_add(bp, args)) {
 		error = xfs_attr3_leaf_to_node(args);
 		if (error)
 			return error;
@@ -574,7 +571,7 @@ xfs_attr_leaf_addname(
 	}
 
 	trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state, args->dp);
-	return error;
+	return 0;
 
 out_brelse:
 	xfs_trans_brelse(args->trans, bp);
@@ -1399,15 +1396,14 @@ xfs_attr_node_try_addname(
 {
 	struct xfs_da_state		*state = attr->xattri_da_state;
 	struct xfs_da_state_blk		*blk;
-	int				error;
+	int				error = 0;
 
 	trace_xfs_attr_node_addname(state->args);
 
 	blk = &state->path.blk[state->path.active-1];
 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
 
-	error = xfs_attr3_leaf_add(blk->bp, state->args);
-	if (error == -ENOSPC) {
+	if (!xfs_attr3_leaf_add(blk->bp, state->args)) {
 		if (state->path.active == 1) {
 			/*
 			 * Its really a single leaf node, but it had
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index b9e98950eb3d81..bcaf28732bfcae 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -47,7 +47,7 @@
  */
 STATIC int xfs_attr3_leaf_create(struct xfs_da_args *args,
 				 xfs_dablk_t which_block, struct xfs_buf **bpp);
-STATIC int xfs_attr3_leaf_add_work(struct xfs_buf *leaf_buffer,
+STATIC void xfs_attr3_leaf_add_work(struct xfs_buf *leaf_buffer,
 				   struct xfs_attr3_icleaf_hdr *ichdr,
 				   struct xfs_da_args *args, int freemap_index);
 STATIC void xfs_attr3_leaf_compact(struct xfs_da_args *args,
@@ -995,10 +995,8 @@ xfs_attr_shortform_to_leaf(
 		xfs_attr_sethash(&nargs);
 		error = xfs_attr3_leaf_lookup_int(bp, &nargs); /* set a->index */
 		ASSERT(error == -ENOATTR);
-		error = xfs_attr3_leaf_add(bp, &nargs);
-		ASSERT(error != -ENOSPC);
-		if (error)
-			goto out;
+		if (!xfs_attr3_leaf_add(bp, &nargs))
+			ASSERT(0);
 		sfe = xfs_attr_sf_nextentry(sfe);
 	}
 	error = 0;
@@ -1343,8 +1341,9 @@ xfs_attr3_leaf_split(
 	struct xfs_da_state_blk	*oldblk,
 	struct xfs_da_state_blk	*newblk)
 {
-	xfs_dablk_t blkno;
-	int error;
+	bool			added;
+	xfs_dablk_t		blkno;
+	int			error;
 
 	trace_xfs_attr_leaf_split(state->args);
 
@@ -1379,10 +1378,10 @@ xfs_attr3_leaf_split(
 	 */
 	if (state->inleaf) {
 		trace_xfs_attr_leaf_add_old(state->args);
-		error = xfs_attr3_leaf_add(oldblk->bp, state->args);
+		added = xfs_attr3_leaf_add(oldblk->bp, state->args);
 	} else {
 		trace_xfs_attr_leaf_add_new(state->args);
-		error = xfs_attr3_leaf_add(newblk->bp, state->args);
+		added = xfs_attr3_leaf_add(newblk->bp, state->args);
 	}
 
 	/*
@@ -1390,13 +1389,15 @@ xfs_attr3_leaf_split(
 	 */
 	oldblk->hashval = xfs_attr_leaf_lasthash(oldblk->bp, NULL);
 	newblk->hashval = xfs_attr_leaf_lasthash(newblk->bp, NULL);
-	return error;
+	if (!added)
+		return -ENOSPC;
+	return 0;
 }
 
 /*
  * Add a name to the leaf attribute list structure.
  */
-int
+bool
 xfs_attr3_leaf_add(
 	struct xfs_buf		*bp,
 	struct xfs_da_args	*args)
@@ -1405,6 +1406,7 @@ xfs_attr3_leaf_add(
 	struct xfs_attr3_icleaf_hdr ichdr;
 	int			tablesize;
 	int			entsize;
+	bool			added = true;
 	int			sum;
 	int			tmp;
 	int			i;
@@ -1433,7 +1435,7 @@ xfs_attr3_leaf_add(
 		if (ichdr.freemap[i].base < ichdr.firstused)
 			tmp += sizeof(xfs_attr_leaf_entry_t);
 		if (ichdr.freemap[i].size >= tmp) {
-			tmp = xfs_attr3_leaf_add_work(bp, &ichdr, args, i);
+			xfs_attr3_leaf_add_work(bp, &ichdr, args, i);
 			goto out_log_hdr;
 		}
 		sum += ichdr.freemap[i].size;
@@ -1445,7 +1447,7 @@ xfs_attr3_leaf_add(
 	 * no good and we should just give up.
 	 */
 	if (!ichdr.holes && sum < entsize)
-		return -ENOSPC;
+		return false;
 
 	/*
 	 * Compact the entries to coalesce free space.
@@ -1458,24 +1460,24 @@ xfs_attr3_leaf_add(
 	 * free region, in freemap[0].  If it is not big enough, give up.
 	 */
 	if (ichdr.freemap[0].size < (entsize + sizeof(xfs_attr_leaf_entry_t))) {
-		tmp = -ENOSPC;
+		added = false;
 		goto out_log_hdr;
 	}
 
-	tmp = xfs_attr3_leaf_add_work(bp, &ichdr, args, 0);
+	xfs_attr3_leaf_add_work(bp, &ichdr, args, 0);
 
 out_log_hdr:
 	xfs_attr3_leaf_hdr_to_disk(args->geo, leaf, &ichdr);
 	xfs_trans_log_buf(args->trans, bp,
 		XFS_DA_LOGRANGE(leaf, &leaf->hdr,
 				xfs_attr3_leaf_hdr_size(leaf)));
-	return tmp;
+	return added;
 }
 
 /*
  * Add a name to a leaf attribute list structure.
  */
-STATIC int
+STATIC void
 xfs_attr3_leaf_add_work(
 	struct xfs_buf		*bp,
 	struct xfs_attr3_icleaf_hdr *ichdr,
@@ -1593,7 +1595,6 @@ xfs_attr3_leaf_add_work(
 		}
 	}
 	ichdr->usedbytes += xfs_attr_leaf_entsize(leaf, args->index);
-	return 0;
 }
 
 /*
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
index bac219589896ad..589f810eedc0d8 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.h
+++ b/fs/xfs/libxfs/xfs_attr_leaf.h
@@ -76,7 +76,7 @@ int	xfs_attr3_leaf_split(struct xfs_da_state *state,
 int	xfs_attr3_leaf_lookup_int(struct xfs_buf *leaf,
 					struct xfs_da_args *args);
 int	xfs_attr3_leaf_getvalue(struct xfs_buf *bp, struct xfs_da_args *args);
-int	xfs_attr3_leaf_add(struct xfs_buf *leaf_buffer,
+bool	xfs_attr3_leaf_add(struct xfs_buf *leaf_buffer,
 				 struct xfs_da_args *args);
 int	xfs_attr3_leaf_remove(struct xfs_buf *leaf_buffer,
 				    struct xfs_da_args *args);
-- 
2.43.0

[PATCH 3/6] xfs: distinguish extra split from real ENOSPC from xfs_attr3_leaf_split

[Christoph Hellwig]

xfs_attr3_leaf_split propagates the need for an extra btree split as
-ENOSPC to it's only caller, but the same return value can also be
returned from xfs_da_grow_inode when it fails to find free space.

Distinguish the two cases by returning 1 for the extra split case instead
of overloading -ENOSPC.

This can be triggered relatively easily with the pending realtime group
support and a file system with a lot of small zones that use metadata
space on the main device.  In this case every about 5-10th run of
xfs/538 runs into the following assert:

	ASSERT(oldblk->magic == XFS_ATTR_LEAF_MAGIC);

in xfs_attr3_leaf_split caused by an allocation failure.  Note that
the allocation failure is caused by another bug that will be fixed
subsequently, but this commit at least sorts out the error handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_attr_leaf.c | 5 ++++-
 fs/xfs/libxfs/xfs_da_btree.c  | 5 +++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index bcaf28732bfcae..92acef51876e4b 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -1334,6 +1334,9 @@ xfs_attr3_leaf_create(
 
 /*
  * Split the leaf node, rebalance, then add the new entry.
+ *
+ * Returns 0 if the entry was added, 1 if a further split is needed or a
+ * negative error number otherwise.
  */
 int
 xfs_attr3_leaf_split(
@@ -1390,7 +1393,7 @@ xfs_attr3_leaf_split(
 	oldblk->hashval = xfs_attr_leaf_lasthash(oldblk->bp, NULL);
 	newblk->hashval = xfs_attr_leaf_lasthash(newblk->bp, NULL);
 	if (!added)
-		return -ENOSPC;
+		return 1;
 	return 0;
 }
 
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 16a529a8878083..17d9e6154f1978 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -593,9 +593,8 @@ xfs_da3_split(
 		switch (oldblk->magic) {
 		case XFS_ATTR_LEAF_MAGIC:
 			error = xfs_attr3_leaf_split(state, oldblk, newblk);
-			if ((error != 0) && (error != -ENOSPC)) {
+			if (error < 0)
 				return error;	/* GROT: attr is inconsistent */
-			}
 			if (!error) {
 				addblk = newblk;
 				break;
@@ -617,6 +616,8 @@ xfs_da3_split(
 				error = xfs_attr3_leaf_split(state, newblk,
 							    &state->extrablk);
 			}
+			if (error == 1)
+				return -ENOSPC;
 			if (error)
 				return error;	/* GROT: attr inconsistent */
 			addblk = newblk;
-- 
2.43.0

[PATCH 4/6] xfs: fold xfs_bmap_alloc_userdata into xfs_bmapi_allocate

[Christoph Hellwig]

Userdata and metadata allocations end up in the same allocation helpers.
Remove the separate xfs_bmap_alloc_userdata function to make this more
clear.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_bmap.c | 73 +++++++++++++++-------------------------
 1 file changed, 28 insertions(+), 45 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 177735c30d273a..6b78340f361ceb 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4167,43 +4167,6 @@ xfs_bmapi_reserve_delalloc(
 	return error;
 }
 
-static int
-xfs_bmap_alloc_userdata(
-	struct xfs_bmalloca	*bma)
-{
-	struct xfs_mount	*mp = bma->ip->i_mount;
-	int			whichfork = xfs_bmapi_whichfork(bma->flags);
-	int			error;
-
-	/*
-	 * Set the data type being allocated. For the data fork, the first data
-	 * in the file is treated differently to all other allocations. For the
-	 * attribute fork, we only need to ensure the allocated range is not on
-	 * the busy list.
-	 */
-	bma->datatype = XFS_ALLOC_NOBUSY;
-	if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK) {
-		bma->datatype |= XFS_ALLOC_USERDATA;
-		if (bma->offset == 0)
-			bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
-
-		if (mp->m_dalign && bma->length >= mp->m_dalign) {
-			error = xfs_bmap_isaeof(bma, whichfork);
-			if (error)
-				return error;
-		}
-
-		if (XFS_IS_REALTIME_INODE(bma->ip))
-			return xfs_bmap_rtalloc(bma);
-	}
-
-	if (unlikely(XFS_TEST_ERROR(false, mp,
-			XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
-		return xfs_bmap_exact_minlen_extent_alloc(bma);
-
-	return xfs_bmap_btalloc(bma);
-}
-
 static int
 xfs_bmapi_allocate(
 	struct xfs_bmalloca	*bma)
@@ -4221,15 +4184,35 @@ xfs_bmapi_allocate(
 	else
 		bma->minlen = 1;
 
-	if (bma->flags & XFS_BMAPI_METADATA) {
-		if (unlikely(XFS_TEST_ERROR(false, mp,
-				XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
-			error = xfs_bmap_exact_minlen_extent_alloc(bma);
-		else
-			error = xfs_bmap_btalloc(bma);
-	} else {
-		error = xfs_bmap_alloc_userdata(bma);
+	if (!(bma->flags & XFS_BMAPI_METADATA)) {
+		/*
+		 * For the data and COW fork, the first data in the file is
+		 * treated differently to all other allocations. For the
+		 * attribute fork, we only need to ensure the allocated range
+		 * is not on the busy list.
+		 */
+		bma->datatype = XFS_ALLOC_NOBUSY;
+		if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK) {
+			bma->datatype |= XFS_ALLOC_USERDATA;
+			if (bma->offset == 0)
+				bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
+
+			if (mp->m_dalign && bma->length >= mp->m_dalign) {
+				error = xfs_bmap_isaeof(bma, whichfork);
+				if (error)
+					return error;
+			}
+		}
 	}
+
+	if ((bma->datatype & XFS_ALLOC_USERDATA) &&
+	    XFS_IS_REALTIME_INODE(bma->ip))
+		error = xfs_bmap_rtalloc(bma);
+	else if (unlikely(XFS_TEST_ERROR(false, mp,
+			XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
+		error = xfs_bmap_exact_minlen_extent_alloc(bma);
+	else
+		error = xfs_bmap_btalloc(bma);
 	if (error)
 		return error;
 	if (bma->blkno == NULLFSBLOCK)
-- 
2.43.0

[PATCH 5/6] xfs: call xfs_bmap_exact_minlen_extent_alloc from xfs_bmap_btalloc

[Christoph Hellwig]

xfs_bmap_exact_minlen_extent_alloc duplicates the args setup in
xfs_bmap_btalloc.  Switch to call it from xfs_bmap_btalloc after
doing the basic setup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_bmap.c | 61 +++++++++-------------------------------
 1 file changed, 13 insertions(+), 48 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 6b78340f361ceb..73c5af9f0affed 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3471,28 +3471,17 @@ xfs_bmap_process_allocated_extent(
 #ifdef DEBUG
 static int
 xfs_bmap_exact_minlen_extent_alloc(
-	struct xfs_bmalloca	*ap)
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args)
 {
-	struct xfs_mount	*mp = ap->ip->i_mount;
-	struct xfs_alloc_arg	args = { .tp = ap->tp, .mp = mp };
-	xfs_fileoff_t		orig_offset;
-	xfs_extlen_t		orig_length;
-	int			error;
-
-	ASSERT(ap->length);
-
 	if (ap->minlen != 1) {
-		ap->blkno = NULLFSBLOCK;
-		ap->length = 0;
+		args->fsbno = NULLFSBLOCK;
 		return 0;
 	}
 
-	orig_offset = ap->offset;
-	orig_length = ap->length;
-
-	args.alloc_minlen_only = 1;
-
-	xfs_bmap_compute_alignments(ap, &args);
+	args->alloc_minlen_only = 1;
+	args->minlen = args->maxlen = ap->minlen;
+	args->total = ap->total;
 
 	/*
 	 * Unlike the longest extent available in an AG, we don't track
@@ -3502,33 +3491,9 @@ xfs_bmap_exact_minlen_extent_alloc(
 	 * we need not be concerned about a drop in performance in
 	 * "debug only" code paths.
 	 */
-	ap->blkno = XFS_AGB_TO_FSB(mp, 0, 0);
+	ap->blkno = XFS_AGB_TO_FSB(ap->ip->i_mount, 0, 0);
 
-	args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
-	args.minlen = args.maxlen = ap->minlen;
-	args.total = ap->total;
-
-	args.alignment = 1;
-	args.minalignslop = 0;
-
-	args.minleft = ap->minleft;
-	args.wasdel = ap->wasdel;
-	args.resv = XFS_AG_RESV_NONE;
-	args.datatype = ap->datatype;
-
-	error = xfs_alloc_vextent_first_ag(&args, ap->blkno);
-	if (error)
-		return error;
-
-	if (args.fsbno != NULLFSBLOCK) {
-		xfs_bmap_process_allocated_extent(ap, &args, orig_offset,
-			orig_length);
-	} else {
-		ap->blkno = NULLFSBLOCK;
-		ap->length = 0;
-	}
-
-	return 0;
+	return xfs_alloc_vextent_first_ag(args, ap->blkno);
 }
 #else
 
@@ -3792,8 +3757,11 @@ xfs_bmap_btalloc(
 	/* Trim the allocation back to the maximum an AG can fit. */
 	args.maxlen = min(ap->length, mp->m_ag_max_usable);
 
-	if ((ap->datatype & XFS_ALLOC_USERDATA) &&
-	    xfs_inode_is_filestream(ap->ip))
+	if (unlikely(XFS_TEST_ERROR(false, mp,
+			XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
+		error = xfs_bmap_exact_minlen_extent_alloc(ap, &args);
+	else if ((ap->datatype & XFS_ALLOC_USERDATA) &&
+			xfs_inode_is_filestream(ap->ip))
 		error = xfs_bmap_btalloc_filestreams(ap, &args, stripe_align);
 	else
 		error = xfs_bmap_btalloc_best_length(ap, &args, stripe_align);
@@ -4208,9 +4176,6 @@ xfs_bmapi_allocate(
 	if ((bma->datatype & XFS_ALLOC_USERDATA) &&
 	    XFS_IS_REALTIME_INODE(bma->ip))
 		error = xfs_bmap_rtalloc(bma);
-	else if (unlikely(XFS_TEST_ERROR(false, mp,
-			XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
-		error = xfs_bmap_exact_minlen_extent_alloc(bma);
 	else
 		error = xfs_bmap_btalloc(bma);
 	if (error)
-- 
2.43.0

[PATCH 6/6] xfs: support lowmode allocations in xfs_bmap_exact_minlen_extent_alloc

[Christoph Hellwig]

Currently the debug-only xfs_bmap_exact_minlen_extent_alloc allocation
variant fails to drop into the lowmode last resort allocator, and
thus can sometimes fail allocations for which the caller has a
transaction block reservation.

Fix this by using xfs_bmap_btalloc_low_space to do the actual allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_bmap.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 73c5af9f0affed..f890d8dc25e47d 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3493,7 +3493,13 @@ xfs_bmap_exact_minlen_extent_alloc(
 	 */
 	ap->blkno = XFS_AGB_TO_FSB(ap->ip->i_mount, 0, 0);
 
-	return xfs_alloc_vextent_first_ag(args, ap->blkno);
+	/*
+	 * Call xfs_bmap_btalloc_low_space here as it first does a "normal" AG
+	 * iteration and then drops args->total to args->minlen, which might be
+	 * required to find an allocation for the transaction reservation when
+	 * the file system is very full.
+	 */
+	return xfs_bmap_btalloc_low_space(ap, args);
 }
 #else
 
-- 
2.43.0

Re: [PATCH 6/6] xfs: support lowmode allocations in xfs_bmap_exact_minlen_extent_alloc

[Chandan Babu R]

On Sat, Aug 24, 2024 at 05:40:12 AM +0200, Christoph Hellwig wrote:
> Currently the debug-only xfs_bmap_exact_minlen_extent_alloc allocation
> variant fails to drop into the lowmode last resort allocator, and
> thus can sometimes fail allocations for which the caller has a
> transaction block reservation.
>
> Fix this by using xfs_bmap_btalloc_low_space to do the actual allocation.
>

The changes look good to me,

Acked-by: Chandan Babu R <chandanbabu@kernel.org>

-- 
Chandan

Re: fix a DEBUG-only assert failure in xfs/538 v2

[Dave Chinner]

On Sat, Aug 24, 2024 at 05:40:06AM +0200, Christoph Hellwig wrote:
> Hi all,
> 
> when testing with very small rtgroups I've seen relatively frequent
> failures in xfs/538 where an assert about the da block type triggers
> that should be entirely impossible to trigger by the expected code
> flow.
> 
> It turns out for this two things had to come together:  a bug in the
> attr code to uses ENOSPC to signal a condition that is not related
> to run out free blocks, but which can also be triggered when we
> actually run out of free blocks, and a debug in the DEBUG only
> xfs_bmap_exact_minlen_extent_alloc allocator trigger only by the
> specific error injection used in this and a few other tests.
> 
> This series tries to fix both issues and clean up the surrounding
> code a bit to make it more obvious.
> 
> Changes since v1:
>  - fix build for !DEBUG builds
>  - improve a comment
>  - fix a comment typo
> 
> Diffstat;
>  xfs_attr.c      |  178 ++++++++++++++++++++++----------------------------------
>  xfs_attr_leaf.c |   40 ++++++------
>  xfs_attr_leaf.h |    2 
>  xfs_bmap.c      |  134 +++++++++++++-----------------------------
>  xfs_da_btree.c  |    5 -
>  5 files changed, 143 insertions(+), 216 deletions(-)

Series looks good.

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