kernel/git/stable/linux.git/fs/ext4/inode.c, branch linux-4.13.y

ext4, project: expand inode extra size if possible

2017-08-06T05:00:49+00:00

When upgrading from old format, try to set project id to old file first time, it will return EOVERFLOW, but if that file is dirtied(touch etc), changing project id will be allowed, this might be confusing for users, we could try to expand @i_extra_isize here too. Reported-by: Zhang Yi Signed-off-by: Miao Xie Signed-off-by: Wang Shilong Signed-off-by: Theodore Ts'o

ext4: restructure ext4_expand_extra_isize

2017-08-06T04:40:01+00:00

Current ext4_expand_extra_isize just tries to expand extra isize, if someone is holding xattr lock or some check fails, it will give up. So rename its name to ext4_try_to_expand_extra_isize. Besides that, we clean up unnecessary check and move some relative checks into it. Signed-off-by: Miao Xie Signed-off-by: Theodore Ts'o Reviewed-by: Wang Shilong

ext4: fix forgetten xattr lock protection in ext4_expand_extra_isize

2017-08-06T04:27:38+00:00

We should avoid the contention between the i_extra_isize update and the inline data insertion, so move the xattr trylock in front of i_extra_isize update. Signed-off-by: Miao Xie Reviewed-by: Wang Shilong

ext4: make xattr inode reads faster

2017-08-06T04:07:01+00:00

ext4_xattr_inode_read() currently reads each block sequentially while waiting for io operation to complete before moving on to the next block. This prevents request merging in block layer. Add a ext4_bread_batch() function that starts reads for all blocks then optionally waits for them to complete. A similar logic is used in ext4_find_entry(), so update that code to use the new function. Signed-off-by: Tahsin Erdogan Signed-off-by: Theodore Ts'o

ext4: correct comment references to ext4_ext_direct_IO()

2017-07-31T02:26:40+00:00

Commit 914f82a32d0268847 "ext4: refactor direct IO code" deleted ext4_ext_direct_IO(), but references to that function remain in comments. Update them to refer to ext4_direct_IO_write(). Signed-off-by: Eric Whitney Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Reviewed-by: Jan Kara

ext4: change fast symlink test to not rely on i_blocks

2017-07-04T04:11:21+00:00

ext4_inode_info->i_data is the storage area for 4 types of data: a) Extents data b) Inline data c) Block map d) Fast symlink data (symlink length < 60) Extents data case is positively identified by EXT4_INODE_EXTENTS flag. Inline data case is also obvious because of EXT4_INODE_INLINE_DATA flag. Distinguishing c) and d) however requires additional logic. This currently relies on i_blocks count. After subtracting external xattr block from i_blocks, if it is greater than 0 then we know that some data blocks exist, so there must be a block map. This logic got broken after ea_inode feature was added. That feature charges the data blocks of external xattr inodes to the referencing inode and so adds them to the i_blocks. To fix this, we could subtract ea_inode blocks by iterating through all xattr entries and then check whether remaining i_blocks count is zero. Besides being complicated, this won't change the fact that the current way of distinguishing between c) and d) is fragile. The alternative solution is to test whether i_size is less than 60 to determine fast symlink case. ext4_symlink() uses the same test to decide whether to store the symlink in i_data. There is one caveat to address before this can work though. If an inode's i_nlink is zero during eviction, its i_size is set to zero and its data is truncated. If system crashes before inode is removed from the orphan list, next boot orphan cleanup may find the inode with zero i_size. So, a symlink that had its data stored in a block may now appear to be a fast symlink. The solution used in this patch is to treat i_size = 0 as a non-fast symlink case. A zero sized symlink is not legal so the only time this can happen is the mentioned scenario. This is also logically correct because a i_size = 0 symlink has no data stored in i_data. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger

ext4: require key for truncate(2) of encrypted file

2017-06-23T23:48:44+00:00

Currently, filesystems allow truncate(2) on an encrypted file without the encryption key. However, it's impossible to correctly handle the case where the size being truncated to is not a multiple of the filesystem block size, because that would require decrypting the final block, zeroing the part beyond i_size, then encrypting the block. As other modifications to encrypted file contents are prohibited without the key, just prohibit truncate(2) as well, making it fail with ENOKEY. Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o

ext4: avoid unnecessary stalls in ext4_evict_inode()

2017-06-23T03:49:46+00:00

These days inode reclaim calls evict_inode() only when it has no pages in the mapping. In that case it is not necessary to wait for transaction commit in ext4_evict_inode() as there can be no pages waiting to be committed. So avoid unnecessary transaction waiting in that case. We still have to keep the check for the case where ext4_evict_inode() gets called from other paths (e.g. umount) where inode still can have some page cache pages. Reported-by: Johannes Weiner Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o

quota: add get_inode_usage callback to transfer multi-inode charges

2017-06-22T15:46:48+00:00

Ext4 ea_inode feature allows storing xattr values in external inodes to be able to store values that are bigger than a block in size. Ext4 also has deduplication support for these type of inodes. With deduplication, the actual storage waste is eliminated but the users of such inodes are still charged full quota for the inodes as if there was no sharing happening in the background. This design requires ext4 to manually charge the users because the inodes are shared. An implication of this is that, if someone calls chown on a file that has such references we need to transfer the quota for the file and xattr inodes. Current dquot_transfer() function implicitly transfers one inode charge. With ea_inode feature, we would like to transfer multiple inode charges. Add get_inode_usage callback which can interrogate the total number of inodes that were charged for a given inode. [ Applied fix from Colin King to make sure the 'ret' variable is initialized on the successful return path. Detected by CoverityScan, CID#1446616 ("Uninitialized scalar variable") --tytso] Signed-off-by: Tahsin Erdogan Signed-off-by: Theodore Ts'o Signed-off-by: Colin Ian King Acked-by: Jan Kara

ext4: xattr inode deduplication

2017-06-22T15:44:55+00:00

Ext4 now supports xattr values that are up to 64k in size (vfs limit). Large xattr values are stored in external inodes each one holding a single value. Once written the data blocks of these inodes are immutable. The real world use cases are expected to have a lot of value duplication such as inherited acls etc. To reduce data duplication on disk, this patch implements a deduplicator that allows sharing of xattr inodes. The deduplication is based on an in-memory hash lookup that is a best effort sharing scheme. When a xattr inode is read from disk (i.e. getxattr() call), its crc32c hash is added to a hash table. Before creating a new xattr inode for a value being set, the hash table is checked to see if an existing inode holds an identical value. If such an inode is found, the ref count on that inode is incremented. On value removal the ref count is decremented and if it reaches zero the inode is deleted. The quota charging for such inodes is manually managed. Every reference holder is charged the full size as if there was no sharing happening. This is consistent with how xattr blocks are also charged. [ Fixed up journal credits calculation to handle inline data and the rare case where an shared xattr block can get freed when two thread race on breaking the xattr block sharing. --tytso ] Signed-off-by: Tahsin Erdogan Signed-off-by: Theodore Ts'o