[PATCH] ext4: fix for fiemap last-block test

[PATCH] ext4: fix for fiemap last-block test

[Eric Sandeen]

Carl Henrik Lunde reported and debugged this; the test for the
last allocated block was comparing bytes to blocks in this test:

	if (logical + length - 1 == EXT_MAX_BLOCK ||
	    ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK)
		flags |= FIEMAP_EXTENT_LAST;

so any extent which ended right at 4G was stopping the extent
walk.  Just replacing these values with the extent block &
length should fix it.

Also give blksize_bits a saner type, and reverse the order 
of the tests to make the more likely case tested first.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Tested-by: Carl Henrik Lunde <chlunde@ping.uio.no>
---

Index: linux-2.6.29.x86_64/fs/ext4/extents.c
===================================================================
--- linux-2.6.29.x86_64.orig/fs/ext4/extents.c
+++ linux-2.6.29.x86_64/fs/ext4/extents.c
@@ -3087,7 +3087,7 @@ static int ext4_ext_fiemap_cb(struct ino
 		       void *data)
 {
 	struct fiemap_extent_info *fieinfo = data;
-	unsigned long blksize_bits = inode->i_sb->s_blocksize_bits;
+	unsigned char blksize_bits = inode->i_sb->s_blocksize_bits;
 	__u64	logical;
 	__u64	physical;
 	__u64	length;
@@ -3134,8 +3134,8 @@ static int ext4_ext_fiemap_cb(struct ino
 	 *
 	 * XXX this might miss a single-block extent at EXT_MAX_BLOCK
 	 */
-	if (logical + length - 1 == EXT_MAX_BLOCK ||
-	    ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK)
+	if (ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK ||
+	    newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK)
 		flags |= FIEMAP_EXTENT_LAST;
 
 	error = fiemap_fill_next_extent(fieinfo, logical, physical,

Re: [PATCH] ext4: fix for fiemap last-block test

[Theodore Tso]

Thanks, I've pulled this into the ext4 patch queue.  While I was
testing this, I found an additional bug in ext4's fiemap handling.
I'll post that fix as a reply to this message.

						- Ted

[PATCH] ext4: fix the length returned by fiemap for an unallocated extent

[Theodore Ts'o]

If the file's blocks have not yet been allocated because of delayed
allocation, the length of the extent returned by fiemap is incorrect.
This commit fixes this bug.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext4/extents.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 86c64ea..e963870 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3234,8 +3234,15 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
 	 * XXX this might miss a single-block extent at EXT_MAX_BLOCK
 	 */
 	if (ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK ||
-	    newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK)
+	    newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK) {
+		loff_t size = i_size_read(inode);
+		loff_t bs = EXT4_BLOCK_SIZE(inode->i_sb);
+
 		flags |= FIEMAP_EXTENT_LAST;
+		if ((flags & FIEMAP_EXTENT_DELALLOC) &&
+		    logical+length > size)
+			length = (size - logical + bs - 1) & ~(bs-1);
+	}
 
 	error = fiemap_fill_next_extent(fieinfo, logical, physical,
 					length, flags);
-- 
1.6.0.4