@@ -753,6 +753,7 @@ xfs_bmap_extents_to_btree(
args.type = XFS_ALLOCTYPE_START_BNO;
args.fsbno = XFS_INO_TO_FSB(mp, ip->i_ino);
} else if (dfops->dop_low) {
+try_another_ag:
args.type = XFS_ALLOCTYPE_START_BNO;
args.fsbno = *firstblock;
} else {
@@ -767,6 +768,21 @@ xfs_bmap_extents_to_btree(
xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
return error;
}
+
+ /*
+ * During a CoW operation, the allocation and bmbt updates occur in
+ * different transactions. The mapping code tries to put new bmbt
+ * blocks near extents being mapped, but the only way to guarantee this
+ * is if the alloc and the mapping happen in a single transaction that
+ * has a block reservation. That isn't the case here, so if we run out
+ * of space we'll try again with another AG.
+ */
+ if (xfs_sb_version_hasreflink(&cur->bc_mp->m_sb) &&
+ args.fsbno == NULLFSBLOCK &&
+ args.type == XFS_ALLOCTYPE_NEAR_BNO) {
+ dfops->dop_low = true;
+ goto try_another_ag;
+ }
/*
* Allocation can't fail, the space was reserved.
*/
@@ -902,6 +918,7 @@ xfs_bmap_local_to_extents(
* file currently fits in an inode.
*/
if (*firstblock == NULLFSBLOCK) {
+try_another_ag:
args.fsbno = XFS_INO_TO_FSB(args.mp, ip->i_ino);
args.type = XFS_ALLOCTYPE_START_BNO;
} else {
@@ -914,6 +931,19 @@ xfs_bmap_local_to_extents(
if (error)
goto done;
+ /*
+ * During a CoW operation, the allocation and bmbt updates occur in
+ * different transactions. The mapping code tries to put new bmbt
+ * blocks near extents being mapped, but the only way to guarantee this
+ * is if the alloc and the mapping happen in a single transaction that
+ * has a block reservation. That isn't the case here, so if we run out
+ * of space we'll try again with another AG.
+ */
+ if (xfs_sb_version_hasreflink(&ip->i_mount->m_sb) &&
+ args.fsbno == NULLFSBLOCK &&
+ args.type == XFS_ALLOCTYPE_NEAR_BNO) {
+ goto try_another_ag;
+ }
/* Can't fail, the space was reserved. */
ASSERT(args.fsbno != NULLFSBLOCK);
ASSERT(args.len == 1);
@@ -453,6 +453,7 @@ xfs_bmbt_alloc_block(
if (args.fsbno == NULLFSBLOCK) {
args.fsbno = be64_to_cpu(start->l);
+try_another_ag:
args.type = XFS_ALLOCTYPE_START_BNO;
/*
* Make sure there is sufficient room left in the AG to
@@ -482,6 +483,22 @@ xfs_bmbt_alloc_block(
if (error)
goto error0;
+ /*
+ * During a CoW operation, the allocation and bmbt updates occur in
+ * different transactions. The mapping code tries to put new bmbt
+ * blocks near extents being mapped, but the only way to guarantee this
+ * is if the alloc and the mapping happen in a single transaction that
+ * has a block reservation. That isn't the case here, so if we run out
+ * of space we'll try again with another AG.
+ */
+ if (xfs_sb_version_hasreflink(&cur->bc_mp->m_sb) &&
+ args.fsbno == NULLFSBLOCK &&
+ args.type == XFS_ALLOCTYPE_NEAR_BNO) {
+ cur->bc_private.b.dfops->dop_low = true;
+ args.fsbno = cur->bc_private.b.firstblock;
+ goto try_another_ag;
+ }
+
if (args.fsbno == NULLFSBLOCK && args.minleft) {
/*
* Could not find an AG with enough free space to satisfy
Prior to the introduction of reflink, allocating a block and mapping it into a file was performed in a single transaction with a single block reservation, and the allocator was supposed to find enough blocks to allocate the extent and any BMBT blocks that might be necessary (unless we're low on space). However, due to the way copy on write works, allocation and mapping have been split into two transactions, which means that we must be able to handle the case where we allocate an extent for CoW but that AG runs out of free space before the blocks can be mapped into a file, and the mapping requires a new BMBT block. When this happens, look in one of the other AGs for a BMBT block instead of taking the FS down. The same applies to the functions that convert a data fork to extents and later btree format. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> --- fs/xfs/libxfs/xfs_bmap.c | 30 ++++++++++++++++++++++++++++++ fs/xfs/libxfs/xfs_bmap_btree.c | 17 +++++++++++++++++ 2 files changed, 47 insertions(+)