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ext4: prevent getting empty inode buffer

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In ext4_get_inode_loc(), we may skip IO and get an zero && uptodate
inode buffer when the inode monopolize an inode block for performance
reason. For most cases, ext4_mark_iloc_dirty() will fill the inode
buffer to make it fine, but we could miss this call if something bad
happened. Finally, __ext4_get_inode_loc_noinmem() may probably get an
empty inode buffer and trigger ext4 error.

For example, if we remove a nonexistent xattr on inode A,
ext4_xattr_set_handle() will return ENODATA before invoking
ext4_mark_iloc_dirty(), it will left an uptodate but zero buffer. We
will get checksum error message in ext4_iget() when getting inode again.

  EXT4-fs error (device sda): ext4_lookup:1784: inode #131074: comm cat: iget: checksum invalid

Even worse, if we allocate another inode B at the same inode block, it
will corrupt the inode A on disk when write back inode B.

So this patch initialize the inode buffer by filling the in-mem inode
contents if we skip read I/O, ensure that the buffer is really uptodate.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210901020955.1657340-4-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi 2021-09-01 10:09:55 +08:00 committed by Theodore Ts'o
parent 9a1bf32c8e
commit de01f48457
1 changed files with 14 additions and 10 deletions
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24
fs/ext4/inode.c
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@ -4380,12 +4380,12 @@ static int ext4_fill_raw_inode(struct inode *inode, struct ext4_inode *raw_inode
/*
* ext4_get_inode_loc returns with an extra refcount against the inode's
* underlying buffer_head on success. If 'in_mem' is true, we have all
* data in memory that is needed to recreate the on-disk version of this
* inode.
* underlying buffer_head on success. If we pass 'inode' and it does not
* have in-inode xattr, we have all inode data in memory that is needed
* to recreate the on-disk version of this inode.
*/
static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
struct ext4_iloc *iloc, int in_mem,
struct inode *inode, struct ext4_iloc *iloc,
ext4_fsblk_t *ret_block)
{
struct ext4_group_desc *gdp;
@ -4431,7 +4431,7 @@ static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
* is the only valid inode in the block, we need not read the
* block.
*/
if (in_mem) {
if (inode && !ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
struct buffer_head *bitmap_bh;
int i, start;
@ -4459,8 +4459,13 @@ static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
}
brelse(bitmap_bh);
if (i == start + inodes_per_block) {
struct ext4_inode *raw_inode =
(struct ext4_inode *) (bh->b_data + iloc->offset);
/* all other inodes are free, so skip I/O */
memset(bh->b_data, 0, bh->b_size);
if (!ext4_test_inode_state(inode, EXT4_STATE_NEW))
ext4_fill_raw_inode(inode, raw_inode);
set_buffer_uptodate(bh);
unlock_buffer(bh);
goto has_buffer;
@ -4521,7 +4526,7 @@ static int __ext4_get_inode_loc_noinmem(struct inode *inode,
ext4_fsblk_t err_blk;
int ret;
ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, iloc, 0,
ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, NULL, iloc,
&err_blk);
if (ret == -EIO)
@ -4536,9 +4541,8 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
ext4_fsblk_t err_blk;
int ret;
/* We have all inode data except xattrs in memory here. */
ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, iloc,
!ext4_test_inode_state(inode, EXT4_STATE_XATTR), &err_blk);
ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, inode, iloc,
&err_blk);
if (ret == -EIO)
ext4_error_inode_block(inode, err_blk, EIO,
@ -4551,7 +4555,7 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
int ext4_get_fc_inode_loc(struct super_block *sb, unsigned long ino,
struct ext4_iloc *iloc)
{
return __ext4_get_inode_loc(sb, ino, iloc, 0, NULL);
return __ext4_get_inode_loc(sb, ino, NULL, iloc, NULL);
}
static bool ext4_should_enable_dax(struct inode *inode)