xfs: Initialize xfs_alloc_arg->total correctly when allocating minlen extents

xfs/538 can cause the following call trace to be printed when executing on a
multi-block directory configuration,

 WARNING: CPU: 1 PID: 2578 at fs/xfs/libxfs/xfs_bmap.c:717 xfs_bmap_extents_to_btree+0x520/0x5d0
 Call Trace:
  ? xfs_buf_rele+0x4f/0x450
  xfs_bmap_add_extent_hole_real+0x747/0x960
  xfs_bmapi_allocate+0x39a/0x440
  xfs_bmapi_write+0x507/0x9e0
  xfs_da_grow_inode_int+0x1cd/0x330
  ? up+0x12/0x60
  xfs_dir2_grow_inode+0x62/0x110
  ? xfs_trans_log_inode+0x234/0x2d0
  xfs_dir2_sf_to_block+0x103/0x940
  ? xfs_dir2_sf_check+0x8c/0x210
  ? xfs_da_compname+0x19/0x30
  ? xfs_dir2_sf_lookup+0xd0/0x3d0
  xfs_dir2_sf_addname+0x10d/0x910
  xfs_dir_createname+0x1ad/0x210
  xfs_create+0x404/0x620
  xfs_generic_create+0x24c/0x320
  path_openat+0xda6/0x1030
  do_filp_open+0x88/0x130
  ? kmem_cache_alloc+0x50/0x210
  ? __cond_resched+0x16/0x40
  ? kmem_cache_alloc+0x50/0x210
  do_sys_openat2+0x97/0x150
  __x64_sys_creat+0x49/0x70
  do_syscall_64+0x33/0x40
  entry_SYSCALL_64_after_hwframe+0x44/0xae

This occurs because xfs_bmap_exact_minlen_extent_alloc() initializes
xfs_alloc_arg->total to xfs_bmalloca->minlen. In the context of
xfs_bmap_exact_minlen_extent_alloc(), xfs_bmalloca->minlen has a value of 1
and hence the space allocator could choose an AG which has less than
xfs_bmalloca->total number of free blocks available. As the transaction
proceeds, one of the future space allocation requests could fail due to
non-availability of free blocks in the AG that was originally chosen.

This commit fixes the bug by assigning xfs_alloc_arg->total to the value of
xfs_bmalloca->total.

Fixes: 301519674699 ("xfs: Introduce error injection to allocate only minlen size extents for files")
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 5574d34..a1d5f50 100644 (file)
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3585,7 +3585,8 @@ xfs_bmap_exact_minlen_extent_alloc(
        args.fsbno = ap->blkno;
        args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
        args.type = XFS_ALLOCTYPE_FIRST_AG;
-       args.total = args.minlen = args.maxlen = ap->minlen;
+       args.minlen = args.maxlen = ap->minlen;
+       args.total = ap->total;
 
        args.alignment = 1;
        args.minalignslop = 0;