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Commit b939e376 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Ts'o
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ext4: Use the ext4_ext_actual_len() helper function 

ext4 uses the high bit of the extent length to encode whether the extent
is intialized or not. The helper function ext4_ext_get_actual_len should
be used to get the actual length of the extent.

This addresses the kernel bug documented here: 
     http://bugzilla.kernel.org/show_bug.cgi?id=9732



kernel BUG at fs/ext4/extents.c:1056!
....
Call Trace:
[<ffffffff88366073>] :ext4dev:ext4_ext_get_blocks+0x5ba/0x8c1
[<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
[<ffffffff812748f6>] _spin_unlock+0x17/0x20
[<ffffffff883400a6>] :jbd2:start_this_handle+0x4e0/0x4fe
[<ffffffff88366564>] :ext4dev:ext4_fallocate+0x175/0x39a
[<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
[<ffffffff81056480>] __lock_acquire+0x4e7/0xc4d
[<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
[<ffffffff810a8de7>] sys_fallocate+0xe4/0x10d
[<ffffffff8100c043>] tracesys+0xd5/0xda

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent dbf9d7da

fs/ext4/extents.c

+13 −11
Original line number Diff line number Diff line
@@ -1029,7 +1029,7 @@ ext4_ext_search_left(struct inode *inode, struct ext4_ext_path *path, 
{

	struct ext4_extent_idx *ix;

	struct ext4_extent *ex;

	int depth;

	int depth, ee_len;



	BUG_ON(path == NULL);

	depth = path->p_depth;
@@ -1043,6 +1043,7 @@ ext4_ext_search_left(struct inode *inode, struct ext4_ext_path *path, 
	 * first one in the file */



	ex = path[depth].p_ext;

	ee_len = ext4_ext_get_actual_len(ex);

	if (*logical < le32_to_cpu(ex->ee_block)) {

		BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);

		while (--depth >= 0) {
@@ -1052,10 +1053,10 @@ ext4_ext_search_left(struct inode *inode, struct ext4_ext_path *path, 
		return 0;

	}



	BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));

	BUG_ON(*logical < (le32_to_cpu(ex->ee_block) + ee_len));



	*logical = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1;

	*phys = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - 1;

	*logical = le32_to_cpu(ex->ee_block) + ee_len - 1;

	*phys = ext_pblock(ex) + ee_len - 1;

	return 0;

}
@@ -1075,7 +1076,7 @@ ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path, 
	struct ext4_extent_idx *ix;

	struct ext4_extent *ex;

	ext4_fsblk_t block;

	int depth;

	int depth, ee_len;



	BUG_ON(path == NULL);

	depth = path->p_depth;
@@ -1089,6 +1090,7 @@ ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path, 
	 * first one in the file */



	ex = path[depth].p_ext;

	ee_len = ext4_ext_get_actual_len(ex);

	if (*logical < le32_to_cpu(ex->ee_block)) {

		BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);

		while (--depth >= 0) {
@@ -1100,7 +1102,7 @@ ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path, 
		return 0;

	}



	BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));

	BUG_ON(*logical < (le32_to_cpu(ex->ee_block) + ee_len));



	if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {

		/* next allocated block in this leaf */
@@ -1316,7 +1318,7 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, 
	if (ext1_ee_len + ext2_ee_len > max_len)

		return 0;

#ifdef AGGRESSIVE_TEST

	if (le16_to_cpu(ex1->ee_len) >= 4)

	if (ext1_ee_len >= 4)

		return 0;

#endif
@@ -2313,7 +2315,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, 
				   - le32_to_cpu(newex.ee_block)

				   + ext_pblock(&newex);

			/* number of remaining blocks in the extent */

			allocated = le16_to_cpu(newex.ee_len) -

			allocated = ext4_ext_get_actual_len(&newex) -

					(iblock - le32_to_cpu(newex.ee_block));

			goto out;

		} else {
@@ -2429,7 +2431,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, 
	newex.ee_len = cpu_to_le16(max_blocks);

	err = ext4_ext_check_overlap(inode, &newex, path);

	if (err)

		allocated = le16_to_cpu(newex.ee_len);

		allocated = ext4_ext_get_actual_len(&newex);

	else

		allocated = max_blocks;
@@ -2461,7 +2463,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, 
		 * but otherwise we'd need to call it every free() */

		ext4_mb_discard_inode_preallocations(inode);

		ext4_free_blocks(handle, inode, ext_pblock(&newex),

					le16_to_cpu(newex.ee_len), 0);

					ext4_ext_get_actual_len(&newex), 0);

		goto out2;

	}
@@ -2470,7 +2472,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, 


	/* previous routine could use block we allocated */

	newblock = ext_pblock(&newex);

	allocated = le16_to_cpu(newex.ee_len);

	allocated = ext4_ext_get_actual_len(&newex);

outnew:

	__set_bit(BH_New, &bh_result->b_state);