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ext4: add nombcache mount option

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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 <adilger@dilger.ca>
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Tahsin Erdogan 2017-06-22 11:55:14 -04:00 committed by Theodore Ts'o
parent b9fc761ea2
commit cdb7ee4c63
3 changed files with 59 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/ext4/ext4.h
View File

@ -1114,6 +1114,7 @@ struct ext4_inode_info {
/*
* Mount flags set via mount options or defaults
*/
#define EXT4_MOUNT_NO_MBCACHE 0x00001 /* Do not use mbcache */
#define EXT4_MOUNT_GRPID 0x00004 /* Create files with directory's group */
#define EXT4_MOUNT_DEBUG 0x00008 /* Some debugging messages */
#define EXT4_MOUNT_ERRORS_CONT 0x00010 /* Continue on errors */

34
fs/ext4/super.c
View File

@ -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_ea_block_cache = ext4_xattr_create_cache();
if (!sbi->s_ea_block_cache) {
ext4_msg(sb, KERN_ERR, "Failed to create ea_block_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_ea_block_cache = ext4_xattr_create_cache();
if (!sbi->s_ea_block_cache) {
ext4_msg(sb, KERN_ERR,
"Failed to create ea_inode_cache");
"Failed to create ea_block_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_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");

52
fs/ext4/xattr.c
View File

@ -991,10 +991,13 @@ 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",
@ -1008,9 +1011,11 @@ 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);
}
}
}
@ -1194,7 +1199,9 @@ 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(ea_block_cache, hash, bh->b_blocknr);
if (ea_block_cache)
mb_cache_entry_delete(ea_block_cache, hash,
bh->b_blocknr);
get_bh(bh);
unlock_buffer(bh);
@ -1214,11 +1221,13 @@ 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(ea_block_cache, hash,
bh->b_blocknr);
if (ce) {
ce->e_reusable = 1;
mb_cache_entry_put(ea_block_cache, ce);
if (ea_block_cache) {
ce = mb_cache_entry_get(ea_block_cache, hash,
bh->b_blocknr);
if (ce) {
ce->e_reusable = 1;
mb_cache_entry_put(ea_block_cache, ce);
}
}
}
@ -1395,6 +1404,9 @@ 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;
@ -1465,8 +1477,9 @@ 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;
@ -1793,8 +1806,9 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
* ext4_xattr_block_set() to reliably detect modified
* block
*/
mb_cache_entry_delete(ea_block_cache, hash,
bs->bh->b_blocknr);
if (ea_block_cache)
mb_cache_entry_delete(ea_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 */);
@ -2883,6 +2897,8 @@ ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
EXT4_XATTR_REFCOUNT_MAX;
int error;
if (!ea_block_cache)
return;
error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
bh->b_blocknr, reusable);
if (error) {
@ -2949,6 +2965,8 @@ ext4_xattr_block_cache_find(struct inode *inode,
struct mb_cache_entry *ce;
struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
if (!ea_block_cache)
return NULL;
if (!header->h_hash)
return NULL; /* never share */
ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);