diff options
| author | Christoph Hellwig <hch@lst.de> | 2026-02-02 07:06:40 +0100 |
|---|---|---|
| committer | Eric Biggers <ebiggers@kernel.org> | 2026-02-04 11:31:54 -0800 |
| commit | f77f281b61183a5c0b87e6a4d101c70bd32c1c79 (patch) | |
| tree | bdca555b35133f7d898fd43472eb815d960d5e51 /fs/ext4 | |
| parent | b0160e4501bb3572d9ef6e4f8edf758193ee37aa (diff) | |
fsverity: use a hashtable to find the fsverity_info
Use the kernel's resizable hash table (rhashtable) to find the
fsverity_info. This way file systems that want to support fsverity don't
have to bloat every inode in the system with an extra pointer. The
trade-off is that looking up the fsverity_info is a bit more expensive
now, but the main operations are still dominated by I/O and hashing
overhead.
The rhashtable implementations requires no external synchronization, and
the _fast versions of the APIs provide the RCU critical sections required
by the implementation. Because struct fsverity_info is only removed on
inode eviction and does not contain a reference count, there is no need
for an extended critical section to grab a reference or validate the
object state. The file open path uses rhashtable_lookup_get_insert_fast,
which can either find an existing object for the hash key or insert a
new one in a single atomic operation, so that concurrent opens never
instantiate duplicate fsverity_info structure. FS_IOC_ENABLE_VERITY must
already be synchronized by a combination of i_rwsem and file system flags
and uses rhashtable_lookup_insert_fast, which errors out on an existing
object for the hash key as an additional safety check.
Because insertion into the hash table now happens before S_VERITY is set,
fsverity just becomes a barrier and a flag check and doesn't have to look
up the fsverity_info at all, so there is only a single lookup per
->read_folio or ->readahead invocation. For btrfs there is an additional
one for each bio completion, while for ext4 and f2fs the fsverity_info
is stored in the per-I/O context and reused for the completion workqueue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Link: https://lore.kernel.org/r/20260202060754.270269-12-hch@lst.de
[EB: folded in fix for missing fsverity_free_info()]
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/ext4.h | 4 | ||||
| -rw-r--r-- | fs/ext4/super.c | 3 | ||||
| -rw-r--r-- | fs/ext4/verity.c | 2 |
3 files changed, 0 insertions, 9 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index a8a448e20ef8..79c319fbf5f0 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1205,10 +1205,6 @@ struct ext4_inode_info { #ifdef CONFIG_FS_ENCRYPTION struct fscrypt_inode_info *i_crypt_info; #endif - -#ifdef CONFIG_FS_VERITY - struct fsverity_info *i_verity_info; -#endif }; /* diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 86131f4d8718..1fb0c90c7a4b 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1484,9 +1484,6 @@ static void init_once(void *foo) #ifdef CONFIG_FS_ENCRYPTION ei->i_crypt_info = NULL; #endif -#ifdef CONFIG_FS_VERITY - ei->i_verity_info = NULL; -#endif } static int __init init_inodecache(void) diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c index 552cc5d81d94..5caa658adc12 100644 --- a/fs/ext4/verity.c +++ b/fs/ext4/verity.c @@ -380,8 +380,6 @@ static int ext4_write_merkle_tree_block(struct file *file, const void *buf, } const struct fsverity_operations ext4_verityops = { - .inode_info_offs = (int)offsetof(struct ext4_inode_info, i_verity_info) - - (int)offsetof(struct ext4_inode_info, vfs_inode), .begin_enable_verity = ext4_begin_enable_verity, .end_enable_verity = ext4_end_enable_verity, .get_verity_descriptor = ext4_get_verity_descriptor, |