diff options
| author | Christoph Hellwig <hch@infradead.org> | 2011-12-01 17:27:40 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-09 08:54:29 -0800 |
| commit | 6a426248da83e544995fc8a494630285260ec4ee (patch) | |
| tree | 592bbae08e1db5db4192c89fe41c5af6d3c41534 | |
| parent | 686da49e5aa50117d8d824c579c3fd9e0318fbc6 (diff) | |
xfs: avoid direct I/O write vs buffered I/O race
commit c58cb165bd44de8aaee9755a144136ae743be116 upstream.
Currently a buffered reader or writer can add pages to the pagecache
while we are waiting for the iolock in xfs_file_dio_aio_write. Prevent
this by re-checking mapping->nrpages after we got the iolock, and if
nessecary upgrade the lock to exclusive mode. To simplify this a bit
only take the ilock inside of xfs_file_aio_write_checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
Cc: Ben Myers <bpm@sgi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/xfs/xfs_file.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 8fd4a0708d30..b7e75c6ba094 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -677,6 +677,7 @@ xfs_file_aio_write_checks( xfs_fsize_t new_size; int error = 0; + xfs_rw_ilock(ip, XFS_ILOCK_EXCL); error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode)); if (error) { xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock); @@ -768,14 +769,24 @@ xfs_file_dio_aio_write( *iolock = XFS_IOLOCK_EXCL; else *iolock = XFS_IOLOCK_SHARED; - xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock); + xfs_rw_ilock(ip, *iolock); ret = xfs_file_aio_write_checks(file, &pos, &count, iolock); if (ret) return ret; + /* + * Recheck if there are cached pages that need invalidate after we got + * the iolock to protect against other threads adding new pages while + * we were waiting for the iolock. + */ + if (mapping->nrpages && *iolock == XFS_IOLOCK_SHARED) { + xfs_rw_iunlock(ip, *iolock); + *iolock = XFS_IOLOCK_EXCL; + xfs_rw_ilock(ip, *iolock); + } + if (mapping->nrpages) { - WARN_ON(*iolock != XFS_IOLOCK_EXCL); ret = -xfs_flushinval_pages(ip, (pos & PAGE_CACHE_MASK), -1, FI_REMAPF_LOCKED); if (ret) @@ -820,7 +831,7 @@ xfs_file_buffered_aio_write( size_t count = ocount; *iolock = XFS_IOLOCK_EXCL; - xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock); + xfs_rw_ilock(ip, *iolock); ret = xfs_file_aio_write_checks(file, &pos, &count, iolock); if (ret) |