[PATCH 45/49] ext4: Use the ext4_ext_actual_len() helper function

From: Theodore Ts'o
Date: Mon Jan 21 2008 - 22:08:23 EST

From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>

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: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
fs/ext4/extents.c | 24 +++++++++++++-----------
1 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 13e3e8c..b6b9ec7 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -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);

--
1.5.4.rc3.31.g1271-dirty

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/