The main purpose of mb cache is to achieve deduplication in
extended attributes. In use cases where opportunity for deduplication
is unlikely, it only adds overhead.
Add a mount option to explicitly turn off mb cache.
Suggested-by: Andreas Dilger <adil...@dilger.ca>
Signed-off-by: Tahsin Erdogan <tah...@google.com>
---
fs/ext4/ext4.h | 1 +
fs/ext4/super.c | 34 +++++++++++++++++++++++-----------
fs/ext4/xattr.c | 52 +++++++++++++++++++++++++++++++++++-----------------
3 files changed, 59 insertions(+), 28 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index cb5ace63796a..65443cbc982a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1149,6 +1149,7 @@ struct ext4_inode_info {
#define EXT4_MOUNT_DIOREAD_NOLOCK 0x400000 /* Enable support for dio read
nolocking */
#define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async
Commit */
+#define EXT4_MOUNT_NO_MBCACHE 0x2000000 /* No mbcache usage */
#define EXT4_MOUNT_DELALLOC 0x8000000 /* Delalloc support */
#define EXT4_MOUNT_DATA_ERR_ABORT 0x10000000 /* Abort on file data write
*/
#define EXT4_MOUNT_BLOCK_VALIDITY 0x20000000 /* Block validity checking */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f347b01ca5ca..c828959b0551 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1336,7 +1336,7 @@ enum {
Opt_inode_readahead_blks, Opt_journal_ioprio,
Opt_dioread_nolock, Opt_dioread_lock,
Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
- Opt_max_dir_size_kb, Opt_nojournal_checksum,
+ Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
};
static const match_table_t tokens = {
@@ -1419,6 +1419,8 @@ static const match_table_t tokens = {
{Opt_noinit_itable, "noinit_itable"},
{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
{Opt_test_dummy_encryption, "test_dummy_encryption"},
+ {Opt_nombcache, "nombcache"},
+ {Opt_nombcache, "no_mbcache"}, /* for backward compatibility */
{Opt_removed, "check=none"}, /* mount option from ext2/3 */
{Opt_removed, "nocheck"}, /* mount option from ext2/3 */
{Opt_removed, "reservation"}, /* mount option from ext2/3 */
@@ -1626,6 +1628,7 @@ static const struct mount_opts {
{Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT},
{Opt_max_dir_size_kb, 0, MOPT_GTE0},
{Opt_test_dummy_encryption, 0, MOPT_GTE0},
+ {Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
{Opt_err, 0, 0}
};
@@ -4080,19 +4083,22 @@ static int ext4_fill_super(struct super_block *sb, void
*data, int silent)
sbi->s_journal->j_commit_callback = ext4_journal_commit_callback;
no_journal:
- sbi->s_mb_block_cache = ext4_xattr_create_cache();
- if (!sbi->s_mb_block_cache) {
- ext4_msg(sb, KERN_ERR, "Failed to create an mb_cache");
- goto failed_mount_wq;
- }
-
- if (ext4_has_feature_ea_inode(sb)) {
- sbi->s_ea_inode_cache = ext4_xattr_create_cache();
- if (!sbi->s_ea_inode_cache) {
+ if (!test_opt(sb, NO_MBCACHE)) {
+ sbi->s_mb_block_cache = ext4_xattr_create_cache();
+ if (!sbi->s_mb_block_cache) {
ext4_msg(sb, KERN_ERR,
- "Failed to create an s_ea_inode_cache");
+ "Failed to create xattr block mb_cache");
goto failed_mount_wq;
}
+
+ if (ext4_has_feature_ea_inode(sb)) {
+ sbi->s_ea_inode_cache = ext4_xattr_create_cache();
+ if (!sbi->s_ea_inode_cache) {
+ ext4_msg(sb, KERN_ERR,
+ "Failed to create ea_inode mb_cache");
+ goto failed_mount_wq;
+ }
+ }
}
if ((DUMMY_ENCRYPTION_ENABLED(sbi) || ext4_has_feature_encrypt(sb)) &&
@@ -4989,6 +4995,12 @@ static int ext4_remount(struct super_block *sb, int
*flags, char *data)
}
}
+ if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_NO_MBCACHE) {
+ ext4_msg(sb, KERN_ERR, "can't enable nombcache during remount");
+ err = -EINVAL;
+ goto restore_opts;
+ }
+
if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX) {
ext4_msg(sb, KERN_WARNING, "warning: refusing change of "
"dax flag with busy inodes while remounting");
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index edef88a2cc7c..0a160d93b52d 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -976,10 +976,13 @@ static int ext4_xattr_inode_update_ref(handle_t *handle,
struct inode *ea_inode,
set_nlink(ea_inode, 1);
ext4_orphan_del(handle, ea_inode);
- hash = ext4_xattr_inode_get_hash(ea_inode);
- mb_cache_entry_create(ea_inode_cache, GFP_NOFS, hash,
- ea_inode->i_ino,
- true /* reusable */);
+ if (ea_inode_cache) {
+ hash = ext4_xattr_inode_get_hash(ea_inode);
+ mb_cache_entry_create(ea_inode_cache,
+ GFP_NOFS, hash,
+ ea_inode->i_ino,
+ true /* reusable */);
+ }
}
} else {
WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
@@ -993,9 +996,11 @@ static int ext4_xattr_inode_update_ref(handle_t *handle,
struct inode *ea_inode,
clear_nlink(ea_inode);
ext4_orphan_add(handle, ea_inode);
- hash = ext4_xattr_inode_get_hash(ea_inode);
- mb_cache_entry_delete(ea_inode_cache, hash,
- ea_inode->i_ino);
+ if (ea_inode_cache) {
+ hash = ext4_xattr_inode_get_hash(ea_inode);
+ mb_cache_entry_delete(ea_inode_cache, hash,
+ ea_inode->i_ino);
+ }
}
}
@@ -1179,7 +1184,9 @@ ext4_xattr_release_block(handle_t *handle, struct inode
*inode,
* This must happen under buffer lock for
* ext4_xattr_block_set() to reliably detect freed block
*/
- mb_cache_entry_delete(mb_block_cache, hash, bh->b_blocknr);
+ if (mb_block_cache)
+ mb_cache_entry_delete(mb_block_cache, hash,
+ bh->b_blocknr);
get_bh(bh);
unlock_buffer(bh);
@@ -1199,11 +1206,13 @@ ext4_xattr_release_block(handle_t *handle, struct inode
*inode,
if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
struct mb_cache_entry *ce;
- ce = mb_cache_entry_get(mb_block_cache, hash,
- bh->b_blocknr);
- if (ce) {
- ce->e_reusable = 1;
- mb_cache_entry_put(mb_block_cache, ce);
+ if (mb_block_cache) {
+ ce = mb_cache_entry_get(mb_block_cache, hash,
+ bh->b_blocknr);
+ if (ce) {
+ ce->e_reusable = 1;
+ mb_cache_entry_put(mb_block_cache, ce);
+ }
}
}
@@ -1382,6 +1391,9 @@ ext4_xattr_inode_cache_find(struct inode *inode, const
void *value,
struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
void *ea_data;
+ if (!ea_inode_cache)
+ return NULL;
+
ce = mb_cache_entry_find_first(ea_inode_cache, hash);
if (!ce)
return NULL;
@@ -1452,8 +1464,9 @@ static int ext4_xattr_inode_lookup_create(handle_t
*handle, struct inode *inode,
return err;
}
- mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
- ea_inode->i_ino, true /* reusable */);
+ if (EA_INODE_CACHE(inode))
+ mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
+ ea_inode->i_ino, true /* reusable */);
*ret_inode = ea_inode;
return 0;
@@ -1780,8 +1793,9 @@ ext4_xattr_block_set(handle_t *handle, struct inode
*inode,
* ext4_xattr_block_set() to reliably detect modified
* block
*/
- mb_cache_entry_delete(mb_block_cache, hash,
- bs->bh->b_blocknr);
+ if (mb_block_cache)
+ mb_cache_entry_delete(mb_block_cache, hash,
+ bs->bh->b_blocknr);
ea_bdebug(bs->bh, "modifying in-place");
error = ext4_xattr_set_entry(i, s, handle, inode,
true /* is_block */);
@@ -2870,6 +2884,8 @@ ext4_xattr_block_cache_insert(struct mb_cache
*mb_block_cache,
EXT4_XATTR_REFCOUNT_MAX;
int error;
+ if (!mb_block_cache)
+ return;
error = mb_cache_entry_create(mb_block_cache, GFP_NOFS, hash,
bh->b_blocknr, reusable);
if (error) {
@@ -2936,6 +2952,8 @@ ext4_xattr_block_cache_find(struct inode *inode,
struct mb_cache_entry *ce;
struct mb_cache *mb_block_cache = MB_BLOCK_CACHE(inode);
+ if (!mb_block_cache)
+ return NULL;
if (!header->h_hash)
return NULL; /* never share */
ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
--
2.13.1.611.g7e3b11ae1-goog
