ext2: convert to mbcache2
The conversion is generally straightforward. We convert filesystem from
a global cache to per-fs one. Similarly to ext4 the tricky part is that
xattr block corresponding to found mbcache entry can get freed before we
get buffer lock for that block. So we have to check whether the entry is
still valid after getting the buffer lock.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 4c69c94..f98ce7e 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -61,6 +61,8 @@
#define rsv_start rsv_window._rsv_start
#define rsv_end rsv_window._rsv_end
+struct mb2_cache;
+
/*
* second extended-fs super-block data in memory
*/
@@ -111,6 +113,7 @@
* of the mount options.
*/
spinlock_t s_lock;
+ struct mb2_cache *s_mb_cache;
};
static inline spinlock_t *
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 2a18841..b78caf2 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -131,7 +131,10 @@
dquot_disable(sb, -1, DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
- ext2_xattr_put_super(sb);
+ if (sbi->s_mb_cache) {
+ ext2_xattr_destroy_cache(sbi->s_mb_cache);
+ sbi->s_mb_cache = NULL;
+ }
if (!(sb->s_flags & MS_RDONLY)) {
struct ext2_super_block *es = sbi->s_es;
@@ -1104,6 +1107,14 @@
ext2_msg(sb, KERN_ERR, "error: insufficient memory");
goto failed_mount3;
}
+
+#ifdef CONFIG_EXT2_FS_XATTR
+ sbi->s_mb_cache = ext2_xattr_create_cache();
+ if (!sbi->s_mb_cache) {
+ ext2_msg(sb, KERN_ERR, "Failed to create an mb_cache");
+ goto failed_mount3;
+ }
+#endif
/*
* set up enough so that it can read an inode
*/
@@ -1149,6 +1160,8 @@
sb->s_id);
goto failed_mount;
failed_mount3:
+ if (sbi->s_mb_cache)
+ ext2_xattr_destroy_cache(sbi->s_mb_cache);
percpu_counter_destroy(&sbi->s_freeblocks_counter);
percpu_counter_destroy(&sbi->s_freeinodes_counter);
percpu_counter_destroy(&sbi->s_dirs_counter);
@@ -1555,20 +1568,17 @@
static int __init init_ext2_fs(void)
{
- int err = init_ext2_xattr();
- if (err)
- return err;
+ int err;
+
err = init_inodecache();
if (err)
- goto out1;
+ return err;
err = register_filesystem(&ext2_fs_type);
if (err)
goto out;
return 0;
out:
destroy_inodecache();
-out1:
- exit_ext2_xattr();
return err;
}
@@ -1576,7 +1586,6 @@
{
unregister_filesystem(&ext2_fs_type);
destroy_inodecache();
- exit_ext2_xattr();
}
MODULE_AUTHOR("Remy Card and others");
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index f57a7ab..7162b48 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -56,7 +56,7 @@
#include <linux/buffer_head.h>
#include <linux/init.h>
#include <linux/slab.h>
-#include <linux/mbcache.h>
+#include <linux/mbcache2.h>
#include <linux/quotaops.h>
#include <linux/rwsem.h>
#include <linux/security.h>
@@ -90,14 +90,12 @@
static int ext2_xattr_set2(struct inode *, struct buffer_head *,
struct ext2_xattr_header *);
-static int ext2_xattr_cache_insert(struct buffer_head *);
+static int ext2_xattr_cache_insert(struct mb2_cache *, struct buffer_head *);
static struct buffer_head *ext2_xattr_cache_find(struct inode *,
struct ext2_xattr_header *);
static void ext2_xattr_rehash(struct ext2_xattr_header *,
struct ext2_xattr_entry *);
-static struct mb_cache *ext2_xattr_cache;
-
static const struct xattr_handler *ext2_xattr_handler_map[] = {
[EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
#ifdef CONFIG_EXT2_FS_POSIX_ACL
@@ -152,6 +150,7 @@
size_t name_len, size;
char *end;
int error;
+ struct mb2_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
name_index, name, buffer, (long)buffer_size);
@@ -196,7 +195,7 @@
goto found;
entry = next;
}
- if (ext2_xattr_cache_insert(bh))
+ if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
ea_idebug(inode, "cache insert failed");
error = -ENODATA;
goto cleanup;
@@ -209,7 +208,7 @@
le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
goto bad_block;
- if (ext2_xattr_cache_insert(bh))
+ if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
ea_idebug(inode, "cache insert failed");
if (buffer) {
error = -ERANGE;
@@ -247,6 +246,7 @@
char *end;
size_t rest = buffer_size;
int error;
+ struct mb2_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
ea_idebug(inode, "buffer=%p, buffer_size=%ld",
buffer, (long)buffer_size);
@@ -281,7 +281,7 @@
goto bad_block;
entry = next;
}
- if (ext2_xattr_cache_insert(bh))
+ if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
ea_idebug(inode, "cache insert failed");
/* list the attribute names */
@@ -483,22 +483,23 @@
/* Here we know that we can set the new attribute. */
if (header) {
- struct mb_cache_entry *ce;
-
/* assert(header == HDR(bh)); */
- ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
- bh->b_blocknr);
lock_buffer(bh);
if (header->h_refcount == cpu_to_le32(1)) {
+ __u32 hash = le32_to_cpu(header->h_hash);
+
ea_bdebug(bh, "modifying in-place");
- if (ce)
- mb_cache_entry_free(ce);
+ /*
+ * This must happen under buffer lock for
+ * ext2_xattr_set2() to reliably detect modified block
+ */
+ mb2_cache_entry_delete_block(EXT2_SB(sb)->s_mb_cache,
+ hash, bh->b_blocknr);
+
/* keep the buffer locked while modifying it. */
} else {
int offset;
- if (ce)
- mb_cache_entry_release(ce);
unlock_buffer(bh);
ea_bdebug(bh, "cloning");
header = kmalloc(bh->b_size, GFP_KERNEL);
@@ -626,6 +627,7 @@
struct super_block *sb = inode->i_sb;
struct buffer_head *new_bh = NULL;
int error;
+ struct mb2_cache *ext2_mb_cache = EXT2_SB(sb)->s_mb_cache;
if (header) {
new_bh = ext2_xattr_cache_find(inode, header);
@@ -653,7 +655,7 @@
don't need to change the reference count. */
new_bh = old_bh;
get_bh(new_bh);
- ext2_xattr_cache_insert(new_bh);
+ ext2_xattr_cache_insert(ext2_mb_cache, new_bh);
} else {
/* We need to allocate a new block */
ext2_fsblk_t goal = ext2_group_first_block_no(sb,
@@ -674,7 +676,7 @@
memcpy(new_bh->b_data, header, new_bh->b_size);
set_buffer_uptodate(new_bh);
unlock_buffer(new_bh);
- ext2_xattr_cache_insert(new_bh);
+ ext2_xattr_cache_insert(ext2_mb_cache, new_bh);
ext2_xattr_update_super_block(sb);
}
@@ -707,19 +709,21 @@
error = 0;
if (old_bh && old_bh != new_bh) {
- struct mb_cache_entry *ce;
-
/*
* If there was an old block and we are no longer using it,
* release the old block.
*/
- ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
- old_bh->b_blocknr);
lock_buffer(old_bh);
if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
+ __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
+
+ /*
+ * This must happen under buffer lock for
+ * ext2_xattr_set2() to reliably detect freed block
+ */
+ mb2_cache_entry_delete_block(ext2_mb_cache,
+ hash, old_bh->b_blocknr);
/* Free the old block. */
- if (ce)
- mb_cache_entry_free(ce);
ea_bdebug(old_bh, "freeing");
ext2_free_blocks(inode, old_bh->b_blocknr, 1);
mark_inode_dirty(inode);
@@ -730,8 +734,6 @@
} else {
/* Decrement the refcount only. */
le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
- if (ce)
- mb_cache_entry_release(ce);
dquot_free_block_nodirty(inode, 1);
mark_inode_dirty(inode);
mark_buffer_dirty(old_bh);
@@ -757,7 +759,6 @@
ext2_xattr_delete_inode(struct inode *inode)
{
struct buffer_head *bh = NULL;
- struct mb_cache_entry *ce;
down_write(&EXT2_I(inode)->xattr_sem);
if (!EXT2_I(inode)->i_file_acl)
@@ -777,19 +778,22 @@
EXT2_I(inode)->i_file_acl);
goto cleanup;
}
- ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
lock_buffer(bh);
if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
- if (ce)
- mb_cache_entry_free(ce);
+ __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
+
+ /*
+ * This must happen under buffer lock for ext2_xattr_set2() to
+ * reliably detect freed block
+ */
+ mb2_cache_entry_delete_block(EXT2_SB(inode->i_sb)->s_mb_cache,
+ hash, bh->b_blocknr);
ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
get_bh(bh);
bforget(bh);
unlock_buffer(bh);
} else {
le32_add_cpu(&HDR(bh)->h_refcount, -1);
- if (ce)
- mb_cache_entry_release(ce);
ea_bdebug(bh, "refcount now=%d",
le32_to_cpu(HDR(bh)->h_refcount));
unlock_buffer(bh);
@@ -806,18 +810,6 @@
}
/*
- * ext2_xattr_put_super()
- *
- * This is called when a file system is unmounted.
- */
-void
-ext2_xattr_put_super(struct super_block *sb)
-{
- mb_cache_shrink(sb->s_bdev);
-}
-
-
-/*
* ext2_xattr_cache_insert()
*
* Create a new entry in the extended attribute cache, and insert
@@ -826,28 +818,20 @@
* Returns 0, or a negative error number on failure.
*/
static int
-ext2_xattr_cache_insert(struct buffer_head *bh)
+ext2_xattr_cache_insert(struct mb2_cache *cache, struct buffer_head *bh)
{
__u32 hash = le32_to_cpu(HDR(bh)->h_hash);
- struct mb_cache_entry *ce;
int error;
- ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
- if (!ce)
- return -ENOMEM;
- error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
+ error = mb2_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr);
if (error) {
- mb_cache_entry_free(ce);
if (error == -EBUSY) {
ea_bdebug(bh, "already in cache (%d cache entries)",
atomic_read(&ext2_xattr_cache->c_entry_count));
error = 0;
}
- } else {
- ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
- atomic_read(&ext2_xattr_cache->c_entry_count));
- mb_cache_entry_release(ce);
- }
+ } else
+ ea_bdebug(bh, "inserting [%x]", (int)hash);
return error;
}
@@ -903,23 +887,17 @@
ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
{
__u32 hash = le32_to_cpu(header->h_hash);
- struct mb_cache_entry *ce;
+ struct mb2_cache_entry *ce;
+ struct mb2_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
if (!header->h_hash)
return NULL; /* never share */
ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
again:
- ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
- hash);
+ ce = mb2_cache_entry_find_first(ext2_mb_cache, hash);
while (ce) {
struct buffer_head *bh;
- if (IS_ERR(ce)) {
- if (PTR_ERR(ce) == -EAGAIN)
- goto again;
- break;
- }
-
bh = sb_bread(inode->i_sb, ce->e_block);
if (!bh) {
ext2_error(inode->i_sb, "ext2_xattr_cache_find",
@@ -927,7 +905,21 @@
inode->i_ino, (unsigned long) ce->e_block);
} else {
lock_buffer(bh);
- if (le32_to_cpu(HDR(bh)->h_refcount) >
+ /*
+ * We have to be careful about races with freeing or
+ * rehashing of xattr block. Once we hold buffer lock
+ * xattr block's state is stable so we can check
+ * whether the block got freed / rehashed or not.
+ * Since we unhash mbcache entry under buffer lock when
+ * freeing / rehashing xattr block, checking whether
+ * entry is still hashed is reliable.
+ */
+ if (hlist_bl_unhashed(&ce->e_hash_list)) {
+ mb2_cache_entry_put(ext2_mb_cache, ce);
+ unlock_buffer(bh);
+ brelse(bh);
+ goto again;
+ } else if (le32_to_cpu(HDR(bh)->h_refcount) >
EXT2_XATTR_REFCOUNT_MAX) {
ea_idebug(inode, "block %ld refcount %d>%d",
(unsigned long) ce->e_block,
@@ -936,13 +928,14 @@
} else if (!ext2_xattr_cmp(header, HDR(bh))) {
ea_bdebug(bh, "b_count=%d",
atomic_read(&(bh->b_count)));
- mb_cache_entry_release(ce);
+ mb2_cache_entry_touch(ext2_mb_cache, ce);
+ mb2_cache_entry_put(ext2_mb_cache, ce);
return bh;
}
unlock_buffer(bh);
brelse(bh);
}
- ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
+ ce = mb2_cache_entry_find_next(ext2_mb_cache, ce);
}
return NULL;
}
@@ -1015,17 +1008,15 @@
#undef BLOCK_HASH_SHIFT
-int __init
-init_ext2_xattr(void)
+#define HASH_BUCKET_BITS 10
+
+struct mb2_cache *ext2_xattr_create_cache(void)
{
- ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
- if (!ext2_xattr_cache)
- return -ENOMEM;
- return 0;
+ return mb2_cache_create(HASH_BUCKET_BITS);
}
-void
-exit_ext2_xattr(void)
+void ext2_xattr_destroy_cache(struct mb2_cache *cache)
{
- mb_cache_destroy(ext2_xattr_cache);
+ if (cache)
+ mb2_cache_destroy(cache);
}
diff --git a/fs/ext2/xattr.h b/fs/ext2/xattr.h
index 60edf29..6ea38aa 100644
--- a/fs/ext2/xattr.h
+++ b/fs/ext2/xattr.h
@@ -53,6 +53,8 @@
#define EXT2_XATTR_SIZE(size) \
(((size) + EXT2_XATTR_ROUND) & ~EXT2_XATTR_ROUND)
+struct mb2_cache;
+
# ifdef CONFIG_EXT2_FS_XATTR
extern const struct xattr_handler ext2_xattr_user_handler;
@@ -65,10 +67,9 @@
extern int ext2_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
extern void ext2_xattr_delete_inode(struct inode *);
-extern void ext2_xattr_put_super(struct super_block *);
-extern int init_ext2_xattr(void);
-extern void exit_ext2_xattr(void);
+extern struct mb2_cache *ext2_xattr_create_cache(void);
+extern void ext2_xattr_destroy_cache(struct mb2_cache *cache);
extern const struct xattr_handler *ext2_xattr_handlers[];
@@ -93,19 +94,7 @@
{
}
-static inline void
-ext2_xattr_put_super(struct super_block *sb)
-{
-}
-
-static inline int
-init_ext2_xattr(void)
-{
- return 0;
-}
-
-static inline void
-exit_ext2_xattr(void)
+static inline void ext2_xattr_destroy_cache(struct mb2_cache *cache)
{
}