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Clear PF_FSTRANS over spl_filp_fallocate() 

The problem described in 2a5d574 also applies to XFS's file or inode
fallocate method.  Both paths may trigger writeback and expose this
issue, see the full stack below.

When layered on XFS a warning will be emitted under CentOS7 when entering
either the file or inode fallocate method with PF_FSTRANS already set.
To avoid triggering this error PF_FSTRANS is cleared and then reset
in vn_space().

WARNING: at fs/xfs/xfs_aops.c:982 xfs_vm_writepage+0x58b/0x5d0

Call Trace:
 [<ffffffff810a1ed5>] warn_slowpath_common+0x95/0xe0
 [<ffffffff810a1f3a>] warn_slowpath_null+0x1a/0x20
 [<ffffffffa0231fdb>] xfs_vm_writepage+0x58b/0x5d0 [xfs]
 [<ffffffff81173ed7>] __writepage+0x17/0x40
 [<ffffffff81176f81>] write_cache_pages+0x251/0x530
 [<ffffffff811772b1>] generic_writepages+0x51/0x80
 [<ffffffffa0230cb0>] xfs_vm_writepages+0x60/0x80 [xfs]
 [<ffffffff81177300>] do_writepages+0x20/0x30
 [<ffffffff8116a5f5>] __filemap_fdatawrite_range+0xb5/0x100
 [<ffffffff8116a6cb>] filemap_write_and_wait_range+0x8b/0xd0
 [<ffffffffa0235bb4>] xfs_free_file_space+0xf4/0x520 [xfs]
 [<ffffffffa023cbce>] xfs_file_fallocate+0x19e/0x2c0 [xfs]
 [<ffffffffa036c6fc>] vn_space+0x3c/0x40 [spl]
 [<ffffffffa0434817>] vdev_file_io_start+0x207/0x260 [zfs]
 [<ffffffffa047170d>] zio_vdev_io_start+0xad/0x2d0 [zfs]
 [<ffffffffa0474942>] zio_execute+0x82/0xe0 [zfs]
 [<ffffffffa036ba7d>] taskq_thread+0x28d/0x5a0 [spl]
 [<ffffffff810c1777>] kthread+0xd7/0xf0
 [<ffffffff8167de2f>] ret_from_fork+0x3f/0x70

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Closes zfsonlinux/zfs#4529
This commit is contained in:
Tim Chase 2016-04-26 06:33:52 -05:00 committed by Brian Behlendorf
parent 3bf657b90c
commit ea2633ad26
1 changed files with 15 additions and 0 deletions
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15
module/spl/spl-vnode.c
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@ -571,6 +571,9 @@ int vn_space(vnode_t *vp, int cmd, struct flock *bfp, int flag,
offset_t offset, void *x6, void *x7)
{
int error = EOPNOTSUPP;
#ifdef FALLOC_FL_PUNCH_HOLE
int fstrans;
#endif
if (cmd != F_FREESP || bfp->l_whence != 0)
return (EOPNOTSUPP);
@ -580,6 +583,14 @@ int vn_space(vnode_t *vp, int cmd, struct flock *bfp, int flag,
ASSERT(bfp->l_start >= 0 && bfp->l_len > 0);
#ifdef FALLOC_FL_PUNCH_HOLE
/*
* May enter XFS which generates a warning when PF_FSTRANS is set.
* To avoid this the flag is cleared over vfs_sync() and then reset.
*/
fstrans = spl_fstrans_check();
if (fstrans)
current->flags &= ~(PF_FSTRANS);
/*
* When supported by the underlying file system preferentially
* use the fallocate() callback to preallocate the space.
@ -587,6 +598,10 @@ int vn_space(vnode_t *vp, int cmd, struct flock *bfp, int flag,
error = -spl_filp_fallocate(vp->v_file,
FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
bfp->l_start, bfp->l_len);
if (fstrans)
current->flags |= PF_FSTRANS;
if (error == 0)
return (0);
#endif