[PATCH 4/4] xfs: Protect xfs_file_aio_write() with sb_start_write - sb_end_write

Jan Kara
2012-01-12T01:21:07Z

Replace racy xfs_wait_for_freeze() check with reliable sb_start_write()
- sb_end_write() locking. Due to lock ranking dictated by the page fault
code we have to call sb_start_write() after we acquire ilock.

CC: Ben Myers <bpm@sgi.com>
CC: Alex Elder <elder@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/xfs/xfs_file.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 753ed9b..c5f879b 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -862,9 +862,11 @@ xfs_file_dio_aio_write(
*iolock = XFS_IOLOCK_SHARED;
}

+ sb_start_write(inode->i_sb);
trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
ret = generic_file_direct_write(iocb, iovp,
&nr_segs, pos, &iocb->ki_pos, count, ocount);
+ sb_end_write(inode->i_sb);

/* No fallback to buffered IO on errors for XFS. */
ASSERT(ret < 0 || ret == count);
@@ -899,6 +901,7 @@ xfs_file_buffered_aio_write(
/* We can write back this queue in page reclaim */
current->backing_dev_info = mapping->backing_dev_info;

+ sb_start_write(inode->i_sb);
write_retry:
trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);
ret = generic_file_buffered_write(iocb, iovp, nr_segs,
@@ -914,6 +917,7 @@ write_retry:
enospc = 1;
goto write_retry;
}
+ sb_end_write(inode->i_sb);
current->backing_dev_info = NULL;
return ret;
}
@@ -945,8 +949,6 @@ xfs_file_aio_write(
if (ocount == 0)
return 0;

- xfs_wait_for_freeze(ip->i_mount, SB_FREEZE_WRITE);
-
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
return -EIO;

--
1.7.1