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authorJan Kara <jack@suse.cz>2016-02-22 11:56:38 -0500
committerTheodore Ts'o <tytso@mit.edu>2016-02-22 11:56:38 -0500
commitbe0726d33cb8f411945884664924bed3cb8c70ee (patch)
tree9460f6b33739e505f29cfa94a13530e8d087a624 /fs/ext2/xattr.c
parent82939d7999dfc1f1998c4b1c12e2f19edbdff272 (diff)
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>
Diffstat (limited to 'fs/ext2/xattr.c')
-rw-r--r--fs/ext2/xattr.c143
1 files changed, 67 insertions, 76 deletions
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index f57a7aba32eb..7162b4869bc3 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 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name,
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 @@ bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
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 @@ found:
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 @@ ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
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 @@ bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
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 @@ bad_block: ext2_error(sb, "ext2_xattr_set",
/* 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 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
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 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
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 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
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 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
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 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
} 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 @@ void
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_xattr_delete_inode(struct inode *inode)
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 @@ cleanup:
}
/*
- * 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 @@ ext2_xattr_put_super(struct super_block *sb)
* 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 @@ static struct buffer_head *
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 @@ again:
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 @@ again:
} 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 @@ static void ext2_xattr_rehash(struct ext2_xattr_header *header,
#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);
}