[PATCH 5.15 054/917] ext4: ensure enough credits in ext4_ext_shift_path_extents

Greg Kroah-Hartman
2021-11-16T01:12:22Z

From: yangerkun <yangerkun@huawei.com>

commit 4268496e48dc681cfa53b92357314b5d7221e625 upstream.

Like ext4_ext_rm_leaf, we can ensure that there are enough credits
before every call that will consume credits. As part of this fix we
fold the functionality of ext4_access_path() into
ext4_ext_shift_path_extents(). This change is needed as a preparation
for the next bugfix patch.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20210903062748.4118886-3-yangerkun@huawei.com
Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/extents.c | 49 +++++++++++++++----------------------------------
1 file changed, 15 insertions(+), 34 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4978,36 +4978,6 @@ int ext4_get_es_cache(struct inode *inod
}

/*
- * ext4_access_path:
- * Function to access the path buffer for marking it dirty.
- * It also checks if there are sufficient credits left in the journal handle
- * to update path.
- */
-static int
-ext4_access_path(handle_t *handle, struct inode *inode,
- struct ext4_ext_path *path)
-{
- int credits, err;
-
- if (!ext4_handle_valid(handle))
- return 0;
-
- /*
- * Check if need to extend journal credits
- * 3 for leaf, sb, and inode plus 2 (bmap and group
- * descriptor) for each block group; assume two block
- * groups
- */
- credits = ext4_writepage_trans_blocks(inode);
- err = ext4_datasem_ensure_credits(handle, inode, 7, credits, 0);
- if (err < 0)
- return err;
-
- err = ext4_ext_get_access(handle, inode, path);
- return err;
-}
-
-/*
* ext4_ext_shift_path_extents:
* Shift the extents of a path structure lying between path[depth].p_ext
* and EXT_LAST_EXTENT(path[depth].p_hdr), by @shift blocks. @SHIFT tells
@@ -5021,6 +4991,7 @@ ext4_ext_shift_path_extents(struct ext4_
int depth, err = 0;
struct ext4_extent *ex_start, *ex_last;
bool update = false;
+ int credits, restart_credits;
depth = path->p_depth;

while (depth >= 0) {
@@ -5030,13 +5001,23 @@ ext4_ext_shift_path_extents(struct ext4_
return -EFSCORRUPTED;

ex_last = EXT_LAST_EXTENT(path[depth].p_hdr);
+ /* leaf + sb + inode */
+ credits = 3;
+ if (ex_start == EXT_FIRST_EXTENT(path[depth].p_hdr)) {
+ update = true;
+ /* extent tree + sb + inode */
+ credits = depth + 2;
+ }

- err = ext4_access_path(handle, inode, path + depth);
+ restart_credits = ext4_writepage_trans_blocks(inode);
+ err = ext4_datasem_ensure_credits(handle, inode, credits,
+ restart_credits, 0);
if (err)
goto out;

- if (ex_start == EXT_FIRST_EXTENT(path[depth].p_hdr))
- update = true;
+ err = ext4_ext_get_access(handle, inode, path + depth);
+ if (err)
+ goto out;

while (ex_start <= ex_last) {
if (SHIFT == SHIFT_LEFT) {
@@ -5067,7 +5048,7 @@ ext4_ext_shift_path_extents(struct ext4_
}

/* Update index too */
- err = ext4_access_path(handle, inode, path + depth);
+ err = ext4_ext_get_access(handle, inode, path + depth);
if (err)
goto out;