2023-01-03 01:47:51

by Jun Nie

Subject: [PATCH v2 0/2] optimize ea_inode block expansion to fix panic

Optimize ea_inode block expansion to avoid memcpy if possible,
panic can be avoided in this way too.

Change vs version 1:
Only error and warning log format in patch 2 is modified per
Theodore's suggestion.

Jun Nie (2):
ext4: optimize ea_inode block expansion
ext4: refuse to create ea block when umounted

fs/ext4/xattr.c | 35 ++++++++++++++++++++++++-----------
1 file changed, 24 insertions(+), 11 deletions(-)

--
2.34.1

2023-01-03 01:48:15

by Jun Nie

Subject: [PATCH v2 1/2] ext4: optimize ea_inode block expansion

Copy ea data from inode entry when expanding ea block if possible.
Then remove the ea entry if expansion success. Thus memcpy to a
temporary buffer may be avoided.

If the expansion fails, we do not need to recovery the removed ea
entry neither in this way.

Signed-off-by: Jun Nie <[email protected]>
---
fs/ext4/xattr.c | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 7decaaf27e82..235a517d9c17 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -2551,9 +2551,8 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,

is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
- buffer = kvmalloc(value_size, GFP_NOFS);
b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
- if (!is || !bs || !buffer || !b_entry_name) {
+ if (!is || !bs || !b_entry_name) {
error = -ENOMEM;
goto out;
}
@@ -2565,12 +2564,18 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,

/* Save the entry name and the entry value */
if (entry->e_value_inum) {
+ buffer = kvmalloc(value_size, GFP_NOFS);
+ if (!buffer) {
+ error = -ENOMEM;
+ goto out;
+ }
+
error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
if (error)
goto out;
} else {
size_t value_offs = le16_to_cpu(entry->e_value_offs);
- memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
+ buffer = (void *)IFIRST(header) + value_offs;
}

memcpy(b_entry_name, entry->e_name, entry->e_name_len);
@@ -2585,25 +2590,26 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
if (error)
goto out;

- /* Remove the chosen entry from the inode */
- error = ext4_xattr_ibody_set(handle, inode, &i, is);
- if (error)
- goto out;
-
i.value = buffer;
i.value_len = value_size;
error = ext4_xattr_block_find(inode, &i, bs);
if (error)
goto out;

- /* Add entry which was removed from the inode into the block */
+ /* Move ea entry from the inode into the block */
error = ext4_xattr_block_set(handle, inode, &i, bs);
if (error)
goto out;
- error = 0;
+
+ /* Remove the chosen entry from the inode */
+ i.value = NULL;
+ i.value_len = 0;
+ error = ext4_xattr_ibody_set(handle, inode, &i, is);
+
out:
kfree(b_entry_name);
- kvfree(buffer);
+ if (entry->e_value_inum && buffer)
+ kvfree(buffer);
if (is)
brelse(is->iloc.bh);
if (bs)
--
2.34.1

2023-02-19 05:41:13

by Theodore Ts'o

Subject: Re: [PATCH v2 0/2] optimize ea_inode block expansion to fix panic

On Tue, 3 Jan 2023 09:45:15 +0800, Jun Nie wrote:
> Optimize ea_inode block expansion to avoid memcpy if possible,
> panic can be avoided in this way too.
>
> Change vs version 1:
> Only error and warning log format in patch 2 is modified per
> Theodore's suggestion.
>
> [...]

Applied, thanks!

[1/2] ext4: optimize ea_inode block expansion
commit: 1e9d62d252812575ded7c620d8fc67c32ff06c16
[2/2] ext4: refuse to create ea block when umounted
commit: f31173c19901a96bb2ebf6bcfec8a08df7095c91

Best regards,
--
Theodore Ts'o <[email protected]>