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Diffstat (limited to 'fs/ext4/xattr.c')
-rw-r--r--fs/ext4/xattr.c166
1 files changed, 100 insertions, 66 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index a95151e875bd..0441e055c8e8 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -545,30 +545,44 @@ static void
ext4_xattr_release_block(handle_t *handle, struct inode *inode,
struct buffer_head *bh)
{
- struct mb_cache_entry *ce = NULL;
- int error = 0;
struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
+ u32 hash, ref;
+ int error = 0;
- ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
BUFFER_TRACE(bh, "get_write_access");
error = ext4_journal_get_write_access(handle, bh);
if (error)
goto out;
lock_buffer(bh);
- if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
+ hash = le32_to_cpu(BHDR(bh)->h_hash);
+ ref = le32_to_cpu(BHDR(bh)->h_refcount);
+ if (ref == 1) {
ea_bdebug(bh, "refcount now=0; freeing");
- if (ce)
- mb_cache_entry_free(ce);
+ /*
+ * This must happen under buffer lock for
+ * ext4_xattr_block_set() to reliably detect freed block
+ */
+ mb_cache_entry_delete_block(ext4_mb_cache, hash, bh->b_blocknr);
get_bh(bh);
unlock_buffer(bh);
ext4_free_blocks(handle, inode, bh, 0, 1,
EXT4_FREE_BLOCKS_METADATA |
EXT4_FREE_BLOCKS_FORGET);
} else {
- le32_add_cpu(&BHDR(bh)->h_refcount, -1);
- if (ce)
- mb_cache_entry_release(ce);
+ ref--;
+ BHDR(bh)->h_refcount = cpu_to_le32(ref);
+ if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
+ struct mb_cache_entry *ce;
+
+ ce = mb_cache_entry_get(ext4_mb_cache, hash,
+ bh->b_blocknr);
+ if (ce) {
+ ce->e_reusable = 1;
+ mb_cache_entry_put(ext4_mb_cache, ce);
+ }
+ }
+
/*
* Beware of this ugliness: Releasing of xattr block references
* from different inodes can race and so we have to protect
@@ -790,8 +804,6 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
if (i->value && i->value_len > sb->s_blocksize)
return -ENOSPC;
if (s->base) {
- ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
- bs->bh->b_blocknr);
BUFFER_TRACE(bs->bh, "get_write_access");
error = ext4_journal_get_write_access(handle, bs->bh);
if (error)
@@ -799,10 +811,15 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
lock_buffer(bs->bh);
if (header(s->base)->h_refcount == cpu_to_le32(1)) {
- if (ce) {
- mb_cache_entry_free(ce);
- ce = NULL;
- }
+ __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
+
+ /*
+ * This must happen under buffer lock for
+ * ext4_xattr_block_set() to reliably detect modified
+ * block
+ */
+ mb_cache_entry_delete_block(ext4_mb_cache, hash,
+ bs->bh->b_blocknr);
ea_bdebug(bs->bh, "modifying in-place");
error = ext4_xattr_set_entry(i, s);
if (!error) {
@@ -826,10 +843,6 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
int offset = (char *)s->here - bs->bh->b_data;
unlock_buffer(bs->bh);
- if (ce) {
- mb_cache_entry_release(ce);
- ce = NULL;
- }
ea_bdebug(bs->bh, "cloning");
s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
error = -ENOMEM;
@@ -872,6 +885,8 @@ inserted:
if (new_bh == bs->bh)
ea_bdebug(new_bh, "keeping");
else {
+ u32 ref;
+
/* The old block is released after updating
the inode. */
error = dquot_alloc_block(inode,
@@ -884,9 +899,40 @@ inserted:
if (error)
goto cleanup_dquot;
lock_buffer(new_bh);
- le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
+ /*
+ * We have to be careful about races with
+ * freeing, rehashing or adding references to
+ * 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. Same rules hold for
+ * e_reusable handling.
+ */
+ if (hlist_bl_unhashed(&ce->e_hash_list) ||
+ !ce->e_reusable) {
+ /*
+ * Undo everything and check mbcache
+ * again.
+ */
+ unlock_buffer(new_bh);
+ dquot_free_block(inode,
+ EXT4_C2B(EXT4_SB(sb),
+ 1));
+ brelse(new_bh);
+ mb_cache_entry_put(ext4_mb_cache, ce);
+ ce = NULL;
+ new_bh = NULL;
+ goto inserted;
+ }
+ ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
+ BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
+ if (ref >= EXT4_XATTR_REFCOUNT_MAX)
+ ce->e_reusable = 0;
ea_bdebug(new_bh, "reusing; refcount now=%d",
- le32_to_cpu(BHDR(new_bh)->h_refcount));
+ ref);
unlock_buffer(new_bh);
error = ext4_handle_dirty_xattr_block(handle,
inode,
@@ -894,7 +940,8 @@ inserted:
if (error)
goto cleanup_dquot;
}
- mb_cache_entry_release(ce);
+ mb_cache_entry_touch(ext4_mb_cache, ce);
+ mb_cache_entry_put(ext4_mb_cache, ce);
ce = NULL;
} else if (bs->bh && s->base == bs->bh->b_data) {
/* We were modifying this block in-place. */
@@ -959,7 +1006,7 @@ getblk_failed:
cleanup:
if (ce)
- mb_cache_entry_release(ce);
+ mb_cache_entry_put(ext4_mb_cache, ce);
brelse(new_bh);
if (!(bs->bh && s->base == bs->bh->b_data))
kfree(s->base);
@@ -1070,6 +1117,17 @@ static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
return 0;
}
+static int ext4_xattr_value_same(struct ext4_xattr_search *s,
+ struct ext4_xattr_info *i)
+{
+ void *value;
+
+ if (le32_to_cpu(s->here->e_value_size) != i->value_len)
+ return 0;
+ value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
+ return !memcmp(value, i->value, i->value_len);
+}
+
/*
* ext4_xattr_set_handle()
*
@@ -1146,6 +1204,13 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
else if (!bs.s.not_found)
error = ext4_xattr_block_set(handle, inode, &i, &bs);
} else {
+ error = 0;
+ /* Xattr value did not change? Save us some work and bail out */
+ if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
+ goto cleanup;
+ if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
+ goto cleanup;
+
error = ext4_xattr_ibody_set(handle, inode, &i, &is);
if (!error && !bs.s.not_found) {
i.value = NULL;
@@ -1512,17 +1577,6 @@ cleanup:
}
/*
- * ext4_xattr_put_super()
- *
- * This is called when a file system is unmounted.
- */
-void
-ext4_xattr_put_super(struct super_block *sb)
-{
- mb_cache_shrink(sb->s_bdev);
-}
-
-/*
* ext4_xattr_cache_insert()
*
* Create a new entry in the extended attribute cache, and insert
@@ -1533,26 +1587,19 @@ ext4_xattr_put_super(struct super_block *sb)
static void
ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
{
- __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
- struct mb_cache_entry *ce;
+ struct ext4_xattr_header *header = BHDR(bh);
+ __u32 hash = le32_to_cpu(header->h_hash);
+ int reusable = le32_to_cpu(header->h_refcount) <
+ EXT4_XATTR_REFCOUNT_MAX;
int error;
- ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
- if (!ce) {
- ea_bdebug(bh, "out of memory");
- return;
- }
- error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
+ error = mb_cache_entry_create(ext4_mb_cache, GFP_NOFS, hash,
+ bh->b_blocknr, reusable);
if (error) {
- mb_cache_entry_free(ce);
- if (error == -EBUSY) {
+ if (error == -EBUSY)
ea_bdebug(bh, "already in cache");
- error = 0;
- }
- } else {
+ } else
ea_bdebug(bh, "inserting [%x]", (int)hash);
- mb_cache_entry_release(ce);
- }
}
/*
@@ -1614,33 +1661,20 @@ ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
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(ext4_mb_cache, inode->i_sb->s_bdev,
- hash);
+ ce = mb_cache_entry_find_first(ext4_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) {
EXT4_ERROR_INODE(inode, "block %lu read error",
(unsigned long) ce->e_block);
- } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
- EXT4_XATTR_REFCOUNT_MAX) {
- ea_idebug(inode, "block %lu refcount %d>=%d",
- (unsigned long) ce->e_block,
- le32_to_cpu(BHDR(bh)->h_refcount),
- EXT4_XATTR_REFCOUNT_MAX);
} else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
*pce = ce;
return bh;
}
brelse(bh);
- ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
+ ce = mb_cache_entry_find_next(ext4_mb_cache, ce);
}
return NULL;
}
@@ -1716,9 +1750,9 @@ static void ext4_xattr_rehash(struct ext4_xattr_header *header,
#define HASH_BUCKET_BITS 10
struct mb_cache *
-ext4_xattr_create_cache(char *name)
+ext4_xattr_create_cache(void)
{
- return mb_cache_create(name, HASH_BUCKET_BITS);
+ return mb_cache_create(HASH_BUCKET_BITS);
}
void ext4_xattr_destroy_cache(struct mb_cache *cache)
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