diff options
| author | Christoph Hellwig <hch@infradead.org> | 2011-08-27 18:42:53 +0400 |
|---|---|---|
| committer | Alex Elder <aelder@sgi.com> | 2011-10-12 06:15:01 +0400 |
| commit | c58cb165bd44de8aaee9755a144136ae743be116 (patch) | |
| tree | 47cf60c7555cf49eb76bbc682bd355e726f51df3 | |
| parent | 859f57ca00805e6c482eef1a7ab073097d02c8ca (diff) | |
| download | linux-c58cb165bd44de8aaee9755a144136ae743be116.tar.xz | |
xfs: avoid direct I/O write vs buffered I/O race
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>
| -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 ee63c4fb3639..06fe97e56e48 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -676,6 +676,7 @@ xfs_file_aio_write_checks( xfs_fsize_t new_size; int error = 0; + xfs_rw_ilock(ip, XFS_ILOCK_EXCL); *new_sizep = 0; restart: error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode)); @@ -798,14 +799,24 @@ 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); + + /* + * 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); + } ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock); if (ret) return ret; if (mapping->nrpages) { - WARN_ON(*iolock != XFS_IOLOCK_EXCL); ret = -xfs_flushinval_pages(ip, (pos & PAGE_CACHE_MASK), -1, FI_REMAPF_LOCKED); if (ret) @@ -851,7 +862,7 @@ 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, new_size, iolock); if (ret) |