| Message ID | 20170518104850.14508-2-jack@suse.cz (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Thu, May 18, 2017 at 12:48:48PM +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 pages are not contiguous. > > 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> > --- Reviewed-by: Brian Foster <bfoster@redhat.com> > fs/xfs/xfs_file.c | 29 +++++++++-------------------- > 1 file changed, 9 insertions(+), 20 deletions(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 35703a801372..f371812e20c6 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1076,17 +1076,6 @@ xfs_find_get_desired_pgoff( > break; > } > > - /* > - * 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. > - */ > - if (type == HOLE_OFF && lastoff == startoff && > - lastoff < page_offset(pvec.pages[0])) { > - found = true; > - break; > - } > - > for (i = 0; i < nr_pages; i++) { > struct page *page = pvec.pages[i]; > loff_t b_offset; > @@ -1098,18 +1087,18 @@ xfs_find_get_desired_pgoff( > * file mapping. However, page->index will not change > * because we have a reference on the page. > * > - * Searching done if the page index is out of range. > - * If the current offset is not reaches the end of > - * the specified search range, there should be a hole > - * between them. > + * If current page offset is beyond where we've ended, > + * we've found a hole. > */ > - if (page->index > end) { > - if (type == HOLE_OFF && lastoff < endoff) { > - *offset = lastoff; > - found = true; > - } > + if (type == HOLE_OFF && lastoff < endoff && > + lastoff < page_offset(pvec.pages[i])) { > + found = true; > + *offset = lastoff; > goto out; > } > + /* Searching done if the page index is out of range. */ > + if (page->index > end) > + goto out; > > lock_page(page); > /* > -- > 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..f371812e20c6 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1076,17 +1076,6 @@ xfs_find_get_desired_pgoff( break; } - /* - * 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. - */ - if (type == HOLE_OFF && lastoff == startoff && - lastoff < page_offset(pvec.pages[0])) { - found = true; - break; - } - for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; loff_t b_offset; @@ -1098,18 +1087,18 @@ xfs_find_get_desired_pgoff( * file mapping. However, page->index will not change * because we have a reference on the page. * - * Searching done if the page index is out of range. - * If the current offset is not reaches the end of - * the specified search range, there should be a hole - * between them. + * If current page offset is beyond where we've ended, + * we've found a hole. */ - if (page->index > end) { - if (type == HOLE_OFF && lastoff < endoff) { - *offset = lastoff; - found = true; - } + if (type == HOLE_OFF && lastoff < endoff && + lastoff < page_offset(pvec.pages[i])) { + found = true; + *offset = lastoff; goto out; } + /* Searching done if the page index is out of range. */ + if (page->index > end) + goto out; lock_page(page); /*
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 pages are not contiguous. 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 | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-)