Commit de01f484 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: prevent getting empty inode buffer 



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: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210901020955.1657340-4-yi.zhang@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 9a1bf32c

fs/ext4/inode.c

+14 −10
Original line number Diff line number Diff line
@@ -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)