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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2018-01-08 10:41:39 -0800 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2018-01-08 10:41:39 -0800 |
| commit | 5a9d929d6e13278df62bd9e3d3ceae8c87ad1eea (patch) | |
| tree | da9fe433e7d6b164e12e9ef74ba7a924698c448b /fs/iomap.c | |
| parent | c017cb5ddfd6326032570d5eba83308c8a9c13a9 (diff) | |
| download | talos-obmc-linux-5a9d929d6e13278df62bd9e3d3ceae8c87ad1eea.tar.gz talos-obmc-linux-5a9d929d6e13278df62bd9e3d3ceae8c87ad1eea.zip | |
iomap: report collisions between directio and buffered writes to userspace
If two programs simultaneously try to write to the same part of a file
via direct IO and buffered IO, there's a chance that the post-diowrite
pagecache invalidation will fail on the dirty page. When this happens,
the dio write succeeded, which means that the page cache is no longer
coherent with the disk!
Programs are not supposed to mix IO types and this is a clear case of
data corruption, so store an EIO which will be reflected to userspace
during the next fsync. Replace the WARN_ON with a ratelimited pr_crit
so that the developers have /some/ kind of breadcrumb to track down the
offending program(s) and file(s) involved.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Diffstat (limited to 'fs/iomap.c')
| -rw-r--r-- | fs/iomap.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/iomap.c b/fs/iomap.c index 47d29ccffaef..e5de7725f18a 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -753,7 +753,8 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) err = invalidate_inode_pages2_range(inode->i_mapping, offset >> PAGE_SHIFT, (offset + dio->size - 1) >> PAGE_SHIFT); - WARN_ON_ONCE(err); + if (err) + dio_warn_stale_pagecache(iocb->ki_filp); } inode_dio_end(file_inode(iocb->ki_filp)); @@ -1018,9 +1019,16 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (ret) goto out_free_dio; + /* + * Try to invalidate cache pages for the range we're direct + * writing. If this invalidation fails, tough, the write will + * still work, but racing two incompatible write paths is a + * pretty crazy thing to do, so we don't support it 100%. + */ ret = invalidate_inode_pages2_range(mapping, start >> PAGE_SHIFT, end >> PAGE_SHIFT); - WARN_ON_ONCE(ret); + if (ret) + dio_warn_stale_pagecache(iocb->ki_filp); ret = 0; if (iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) && |
