On Wed 01-09-21 10:09:55, Zhang Yi wrote:
> 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@xxxxxxxxxx>
Looks good. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/inode.c | 24 ++++++++++++++----------
> 1 file changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 3c36e701e30e..a8388ec91f9f 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4441,12 +4441,12 @@ 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;
> @@ -4486,7 +4486,7 @@ 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;
>
> @@ -4514,8 +4514,13 @@ 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;
> @@ -4576,7 +4581,7 @@ 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)
> @@ -4591,9 +4596,8 @@ 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,
> @@ -4606,7 +4610,7 @@ 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)
> --
> 2.31.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
