fiemap: fix problem with setting FIEMAP_EXTENT_LAST

Fix a problem where the generic block based fiemap stuff would not properly set FIEMAP_EXTENT_LAST on the last extent. I've reworked things to keep track if we go past the EOF, and mark the last extent properly. The problem was reported by and tested by Eric Sandeen. Tested-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Josef Bacik <jbacik@redhat.com> Cc: <linux-ext4@vger.kernel.org> Cc: <xfs-masters@oss.sgi.com> Cc: <linux-btrfs@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <Joel.Becker@oracle.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fiemap: fix problem with setting FIEMAP_EXTENT_LAST
Fix a problem where the generic block based fiemap stuff would not properly set FIEMAP_EXTENT_LAST on the last extent. I've reworked things to keep track if we go past the EOF, and mark the last extent properly. The problem was reported by and tested by Eric Sandeen. Tested-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Josef Bacik <jbacik@redhat.com> Cc: <linux-ext4@vger.kernel.org> Cc: <xfs-masters@oss.sgi.com> Cc: <linux-btrfs@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <Joel.Becker@oracle.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Josef Bacik · Linus Torvalds
1 parent 57adc4d2db
Showing 1 changed file with 55 additions and 20 deletions Side-by-side Diff
fs/ioctl.c
@@ -258,7 +258,7 @@
 	long long length = 0, map_len = 0;
 	u64 logical = 0, phys = 0, size = 0;
 	u32 flags = FIEMAP_EXTENT_MERGED;
-	int ret = 0;
+	int ret = 0, past_eof = 0, whole_file = 0;
  
 	if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
 		return ret;
@@ -266,6 +266,9 @@
 	start_blk = logical_to_blk(inode, start);
  
 	length = (long long)min_t(u64, len, i_size_read(inode));
+	if (length < len)
+		whole_file = 1;
+
 	map_len = length;
  
 	do {
  
  
@@ -282,11 +285,26 @@
  
 		/* HOLE */
 		if (!buffer_mapped(&tmp)) {
+			length -= blk_to_logical(inode, 1);
+			start_blk++;
+
 			/*
+			 * we want to handle the case where there is an
+			 * allocated block at the front of the file, and then
+			 * nothing but holes up to the end of the file properly,
+			 * to make sure that extent at the front gets properly
+			 * marked with FIEMAP_EXTENT_LAST
+			 */
+			if (!past_eof &&
+			    blk_to_logical(inode, start_blk) >=
+			    blk_to_logical(inode, 0)+i_size_read(inode))
+				past_eof = 1;
+
+			/*
 			 * first hole after going past the EOF, this is our
 			 * last extent
 			 */
-			if (length <= 0) {
+			if (past_eof && size) {
 				flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 				ret = fiemap_fill_next_extent(fieinfo, logical,
 							      phys, size,
  
  
  
  
@@ -294,18 +312,40 @@
 				break;
 			}
  
-			length -= blk_to_logical(inode, 1);
-
 			/* if we have holes up to/past EOF then we're done */
-			if (length <= 0)
+			if (length <= 0 || past_eof)
 				break;
-
-			start_blk++;
 		} else {
-			if (length <= 0 && size) {
+			/*
+			 * we have gone over the length of what we wanted to
+			 * map, and it wasn't the entire file, so add the extent
+			 * we got last time and exit.
+			 *
+			 * This is for the case where say we want to map all the
+			 * way up to the second to the last block in a file, but
+			 * the last block is a hole, making the second to last
+			 * block FIEMAP_EXTENT_LAST.  In this case we want to
+			 * see if there is a hole after the second to last block
+			 * so we can mark it properly.  If we found data after
+			 * we exceeded the length we were requesting, then we
+			 * are good to go, just add the extent to the fieinfo
+			 * and break
+			 */
+			if (length <= 0 && !whole_file) {
 				ret = fiemap_fill_next_extent(fieinfo, logical,
 							      phys, size,
 							      flags);
+				break;
+			}
+
+			/*
+			 * if size != 0 then we know we already have an extent
+			 * to add, so add it.
+			 */
+			if (size) {
+				ret = fiemap_fill_next_extent(fieinfo, logical,
+							      phys, size,
+							      flags);
 				if (ret)
 					break;
 			}
  
@@ -319,19 +359,14 @@
 			start_blk += logical_to_blk(inode, size);
  
 			/*
-			 * if we are past the EOF we need to loop again to see
-			 * if there is a hole so we can mark this extent as the
-			 * last one, and if not keep mapping things until we
-			 * find a hole, or we run out of slots in the extent
-			 * array
+			 * If we are past the EOF, then we need to make sure as
+			 * soon as we find a hole that the last extent we found
+			 * is marked with FIEMAP_EXTENT_LAST
 			 */
-			if (length <= 0)
-				continue;
-
-			ret = fiemap_fill_next_extent(fieinfo, logical, phys,
-						      size, flags);
-			if (ret)
-				break;
+			if (!past_eof &&
+			    logical+size >=
+			    blk_to_logical(inode, 0)+i_size_read(inode))
+				past_eof = 1;
 		}
 		cond_resched();
 	} while (1);
...	...	@@ -258,7 +258,7 @@
258	258	long long length = 0, map_len = 0;
259	259	u64 logical = 0, phys = 0, size = 0;
260	260	u32 flags = FIEMAP_EXTENT_MERGED;
261		- int ret = 0;
	261	+ int ret = 0, past_eof = 0, whole_file = 0;
262	262
263	263	if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
264	264	return ret;
...	...	@@ -266,6 +266,9 @@
266	266	start_blk = logical_to_blk(inode, start);
267	267
268	268	length = (long long)min_t(u64, len, i_size_read(inode));
	269	+ if (length < len)
	270	+ whole_file = 1;
	271	+
269	272	map_len = length;
270	273
271	274	do {
272	275
273	276
...	...	@@ -282,11 +285,26 @@
282	285
283	286	/* HOLE */
284	287	if (!buffer_mapped(&tmp)) {
	288	+ length -= blk_to_logical(inode, 1);
	289	+ start_blk++;
	290	+
285	291	/*
	292	+ * we want to handle the case where there is an
	293	+ * allocated block at the front of the file, and then
	294	+ * nothing but holes up to the end of the file properly,
	295	+ * to make sure that extent at the front gets properly
	296	+ * marked with FIEMAP_EXTENT_LAST
	297	+ */
	298	+ if (!past_eof &&
	299	+ blk_to_logical(inode, start_blk) >=
	300	+ blk_to_logical(inode, 0)+i_size_read(inode))
	301	+ past_eof = 1;
	302	+
	303	+ /*
286	304	* first hole after going past the EOF, this is our
287	305	* last extent
288	306	*/
289		- if (length <= 0) {
	307	+ if (past_eof && size) {
290	308	flags = FIEMAP_EXTENT_MERGED\|FIEMAP_EXTENT_LAST;
291	309	ret = fiemap_fill_next_extent(fieinfo, logical,
292	310	phys, size,
293	311
294	312
295	313
296	314
...	...	@@ -294,18 +312,40 @@
294	312	break;
295	313	}
296	314
297		- length -= blk_to_logical(inode, 1);
298		-
299	315	/* if we have holes up to/past EOF then we're done */
300		- if (length <= 0)
	316	+ if (length <= 0 \|\| past_eof)
301	317	break;
302		-
303		- start_blk++;
304	318	} else {
305		- if (length <= 0 && size) {
	319	+ /*
	320	+ * we have gone over the length of what we wanted to
	321	+ * map, and it wasn't the entire file, so add the extent
	322	+ * we got last time and exit.
	323	+ *
	324	+ * This is for the case where say we want to map all the
	325	+ * way up to the second to the last block in a file, but
	326	+ * the last block is a hole, making the second to last
	327	+ * block FIEMAP_EXTENT_LAST. In this case we want to
	328	+ * see if there is a hole after the second to last block
	329	+ * so we can mark it properly. If we found data after
	330	+ * we exceeded the length we were requesting, then we
	331	+ * are good to go, just add the extent to the fieinfo
	332	+ * and break
	333	+ */
	334	+ if (length <= 0 && !whole_file) {
306	335	ret = fiemap_fill_next_extent(fieinfo, logical,
307	336	phys, size,
308	337	flags);
	338	+ break;
	339	+ }
	340	+
	341	+ /*
	342	+ * if size != 0 then we know we already have an extent
	343	+ * to add, so add it.
	344	+ */
	345	+ if (size) {
	346	+ ret = fiemap_fill_next_extent(fieinfo, logical,
	347	+ phys, size,
	348	+ flags);
309	349	if (ret)
310	350	break;
311	351	}
312	352
...	...	@@ -319,19 +359,14 @@
319	359	start_blk += logical_to_blk(inode, size);
320	360
321	361	/*
322		- * if we are past the EOF we need to loop again to see
323		- * if there is a hole so we can mark this extent as the
324		- * last one, and if not keep mapping things until we
325		- * find a hole, or we run out of slots in the extent
326		- * array
	362	+ * If we are past the EOF, then we need to make sure as
	363	+ * soon as we find a hole that the last extent we found
	364	+ * is marked with FIEMAP_EXTENT_LAST
327	365	*/
328		- if (length <= 0)
329		- continue;
330		-
331		- ret = fiemap_fill_next_extent(fieinfo, logical, phys,
332		- size, flags);
333		- if (ret)
334		- break;
	366	+ if (!past_eof &&
	367	+ logical+size >=
	368	+ blk_to_logical(inode, 0)+i_size_read(inode))
	369	+ past_eof = 1;
335	370	}
336	371	cond_resched();
337	372	} while (1);