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ext4: teach ext4_ext_find_extent() to realloc path if necessary

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This adds additional safety in case for some reason we end reusing a
path structure which isn't big enough for current depth of the inode.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2014-09-01 14:40:09 -04:00
parent b7ea89ad0a
commit 10809df84a
2 changed files with 11 additions and 10 deletions
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1
fs/ext4/ext4_extents.h
View File

@ -123,6 +123,7 @@ find_ext4_extent_tail(struct ext4_extent_header *eh)
struct ext4_ext_path { struct ext4_ext_path {
ext4_fsblk_t p_block; ext4_fsblk_t p_block;
__u16 p_depth; __u16 p_depth;
__u16 p_maxdepth;
struct ext4_extent *p_ext; struct ext4_extent *p_ext;
struct ext4_extent_idx *p_idx; struct ext4_extent_idx *p_idx;
struct ext4_extent_header *p_hdr; struct ext4_extent_header *p_hdr;

20
fs/ext4/extents.c
View File

@ -869,14 +869,20 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
eh = ext_inode_hdr(inode); eh = ext_inode_hdr(inode);
depth = ext_depth(inode); depth = ext_depth(inode);
if (path) if (path) {
ext4_ext_drop_refs(path); ext4_ext_drop_refs(path);
else { if (depth > path[0].p_maxdepth) {
kfree(path);
*orig_path = path = NULL;
}
}
if (!path) {
/* account possible depth increase */ /* account possible depth increase */
path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2), path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
GFP_NOFS); GFP_NOFS);
if (unlikely(!path)) if (unlikely(!path))
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
path[0].p_maxdepth = depth + 1;
} }
path[0].p_hdr = eh; path[0].p_hdr = eh;
path[0].p_bh = NULL; path[0].p_bh = NULL;
@ -1820,6 +1826,7 @@ static void ext4_ext_try_to_merge_up(handle_t *handle,
sizeof(struct ext4_extent_idx); sizeof(struct ext4_extent_idx);
s += sizeof(struct ext4_extent_header); s += sizeof(struct ext4_extent_header);
path[1].p_maxdepth = path[0].p_maxdepth;
memcpy(path[0].p_hdr, path[1].p_hdr, s); memcpy(path[0].p_hdr, path[1].p_hdr, s);
path[0].p_depth = 0; path[0].p_depth = 0;
path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) + path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
@ -2150,12 +2157,6 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
/* find extent for this block */ /* find extent for this block */
down_read(&EXT4_I(inode)->i_data_sem); down_read(&EXT4_I(inode)->i_data_sem);
if (path && ext_depth(inode) != depth) {
/* depth was changed. we have to realloc path */
kfree(path);
path = NULL;
}
path = ext4_ext_find_extent(inode, block, &path, 0); path = ext4_ext_find_extent(inode, block, &path, 0);
if (IS_ERR(path)) { if (IS_ERR(path)) {
up_read(&EXT4_I(inode)->i_data_sem); up_read(&EXT4_I(inode)->i_data_sem);
@ -2173,7 +2174,6 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
} }
ex = path[depth].p_ext; ex = path[depth].p_ext;
next = ext4_ext_next_allocated_block(path); next = ext4_ext_next_allocated_block(path);
ext4_ext_drop_refs(path);
flags = 0; flags = 0;
exists = 0; exists = 0;
@ -2897,7 +2897,7 @@ again:
ext4_journal_stop(handle); ext4_journal_stop(handle);
return -ENOMEM; return -ENOMEM;
} }
path[0].p_depth = depth; path[0].p_maxdepth = path[0].p_depth = depth;
path[0].p_hdr = ext_inode_hdr(inode); path[0].p_hdr = ext_inode_hdr(inode);
i = 0; i = 0;