xfs: Fix missed holes in SEEK_HOLE implementation (5375023a) · Commits · 戴 / test

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: Signed-off-by:

Jan Kara <jack@suse.cz> Reviewed-by:

Brian Foster <bfoster@redhat.com> Reviewed-by:

Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by:

Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_file.c

+9 −20

Original line number	Original line	Diff line number	Diff line
	@@ -1076,17 +1076,6 @@ xfs_find_get_desired_pgoff(
	break;		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++) {		for (i = 0; i < nr_pages; i++) {
	struct page *page = pvec.pages[i];		struct page *page = pvec.pages[i];
	loff_t b_offset;		loff_t b_offset;
	@@ -1098,18 +1087,18 @@ xfs_find_get_desired_pgoff(
	* file mapping. However, page->index will not change		* file mapping. However, page->index will not change
	* because we have a reference on the page.		* because we have a reference on the page.
	*		*
	* Searching done if the page index is out of range.		* If current page offset is beyond where we've ended,
	* If the current offset is not reaches the end of		* we've found a hole.
	* the specified search range, there should be a hole
	* between them.
	*/		*/
	if (page->index > end) {		if (type == HOLE_OFF && lastoff < endoff &&
	if (type == HOLE_OFF && lastoff < endoff) {		lastoff < page_offset(pvec.pages[i])) {
	*offset = lastoff;
	found = true;		found = true;
	}		*offset = lastoff;
	goto out;		goto out;
	}		}
			/* Searching done if the page index is out of range. */
			if (page->index > end)
			goto out;

	lock_page(page);		lock_page(page);
	/*		/*

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