| Message ID | 20170511165023.29887-1-jack@suse.cz (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Thu, May 11, 2017 at 06:50:22PM +0200, Jan Kara wrote: > XFS SEEK_HOLE implementation could miss a hole in an unwritten extent as > can be seen by the following command: > > xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k" > -c "seek -h 0" file > wrote 57344/57344 bytes at offset 0 > 56 KiB, 14 ops; 0.0000 sec (49.312 MiB/sec and 12623.9856 ops/sec) > wrote 8192/8192 bytes at offset 131072 > 8 KiB, 2 ops; 0.0000 sec (70.383 MiB/sec and 18018.0180 ops/sec) > Whence Result > HOLE 139264 > > Where we can see that hole at offset 56k was just ignored by SEEK_HOLE > implementation. The bug is in xfs_find_get_desired_pgoff() which does > not properly detect the case when a first page in the pagevec has larger > index than expected (and even if the condition was right, we would fail > to update the returned offset). > > Fix the problem by properly detecting when found page has larger offset > than expected. > > CC: stable@vger.kernel.org > Fixes: d126d43f631f996daeee5006714fed914be32368 > Signed-off-by: Jan Kara <jack@suse.cz> Looks ok, will test... Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > --- > fs/xfs/xfs_file.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 35703a801372..df51c025adfe 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1077,13 +1077,12 @@ xfs_find_get_desired_pgoff( > } > > /* > - * At lease we found one page. If this is the first time we > - * step into the loop, and if the first page index offset is > - * greater than the given search offset, a hole was found. > + * At least we found one page. If the current offset is smaller > + * than the first page offset, a hole was found. > */ > - if (type == HOLE_OFF && lastoff == startoff && > - lastoff < page_offset(pvec.pages[0])) { > + if (type == HOLE_OFF && lastoff < page_offset(pvec.pages[0])) { > found = true; > + *offset = lastoff; > break; > } > > -- > 2.12.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 35703a801372..df51c025adfe 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1077,13 +1077,12 @@ xfs_find_get_desired_pgoff( } /* - * At lease we found one page. If this is the first time we - * step into the loop, and if the first page index offset is - * greater than the given search offset, a hole was found. + * At least we found one page. If the current offset is smaller + * than the first page offset, a hole was found. */ - if (type == HOLE_OFF && lastoff == startoff && - lastoff < page_offset(pvec.pages[0])) { + if (type == HOLE_OFF && lastoff < page_offset(pvec.pages[0])) { found = true; + *offset = lastoff; break; }
XFS SEEK_HOLE implementation could miss a hole in an unwritten extent as can be seen by the following command: xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k" -c "seek -h 0" file wrote 57344/57344 bytes at offset 0 56 KiB, 14 ops; 0.0000 sec (49.312 MiB/sec and 12623.9856 ops/sec) wrote 8192/8192 bytes at offset 131072 8 KiB, 2 ops; 0.0000 sec (70.383 MiB/sec and 18018.0180 ops/sec) Whence Result HOLE 139264 Where we can see that hole at offset 56k was just ignored by SEEK_HOLE implementation. The bug is in xfs_find_get_desired_pgoff() which does not properly detect the case when a first page in the pagevec has larger index than expected (and even if the condition was right, we would fail to update the returned offset). Fix the problem by properly detecting when found page has larger offset than expected. CC: stable@vger.kernel.org Fixes: d126d43f631f996daeee5006714fed914be32368 Signed-off-by: Jan Kara <jack@suse.cz> --- fs/xfs/xfs_file.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)