Re: [PATCH 27/28] ext4: xattr inode deduplication

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On Wed, May 31, 2017 at 01:15:16AM -0700, Tahsin Erdogan wrote:
> Ext4 now supports xattr values that are up to 64k in size (vfs limit).
> Large xattr values are stored in external inodes each one holding a
> single value. Once written the data blocks of these inodes are immutable.
> 
> The real world use cases are expected to have a lot of value duplication
> such as inherited acls etc. To reduce data duplication on disk, this patch
> implements a deduplicator that allows sharing of xattr inodes.
> 
> The deduplication is based on an in-memory hash lookup that is a best
> effort sharing scheme. When a xattr inode is read from disk (i.e.
> getxattr() call), its crc32c hash is added to a hash table. Before
> creating a new xattr inode for a value being set, the hash table is
> checked to see if an existing inode holds an identical value. If such an
> inode is found, the ref count on that inode is incremented. On value
> removal the ref count is decremented and if it reaches zero the inode is
> deleted.
> 
> The quota charging for such inodes is manually managed. Every reference
> holder is charged the full size as if there was no sharing happening.
> This is consistent with how xattr blocks are also charged.
> 
> Signed-off-by: Tahsin Erdogan <tahsin@xxxxxxxxxx>
> ---
>  fs/ext4/acl.c   |    5 +-
>  fs/ext4/ext4.h  |    7 +-
>  fs/ext4/inode.c |    9 +-
>  fs/ext4/super.c |   22 +-
>  fs/ext4/xattr.c | 1073 +++++++++++++++++++++++++++++++++++++++++++------------
>  fs/ext4/xattr.h |   17 +-
>  fs/mbcache.c    |    9 +-
>  7 files changed, 881 insertions(+), 261 deletions(-)
> 
> diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
> index 74f7ac539e00..8db03e5c78bc 100644
> --- a/fs/ext4/acl.c
> +++ b/fs/ext4/acl.c
> @@ -238,7 +238,10 @@ ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>  	if (error)
>  		return error;
>  retry:
> -	credits = ext4_xattr_set_credits(inode, acl_size);
> +	error = ext4_xattr_set_credits(inode, acl_size, &credits);
> +	if (error)
> +		return error;
> +
>  	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
>  	if (IS_ERR(handle))
>  		return PTR_ERR(handle);
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index d79d8d7bee88..79f06290e723 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1517,6 +1517,7 @@ struct ext4_sb_info {
>  	long s_es_nr_inode;
>  	struct ext4_es_stats s_es_stats;
>  	struct mb_cache *s_mb_cache;
> +	struct mb_cache *s_ea_inode_cache;
>  	spinlock_t s_es_lock ____cacheline_aligned_in_smp;
>  
>  	/* Ratelimit ext4 messages. */
> @@ -2099,7 +2100,11 @@ static inline struct ext4_inode *ext4_raw_inode(struct ext4_iloc *iloc)
>  	return (struct ext4_inode *) (iloc->bh->b_data + iloc->offset);
>  }
>  
> -#define ext4_is_quota_file(inode) IS_NOQUOTA(inode)
> +static inline bool ext4_is_quota_file(struct inode *inode)
> +{
> +	return IS_NOQUOTA(inode) &&
> +	       !(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL);
> +}
>  
>  /*
>   * This structure is stuffed into the struct file's private_data field
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 4d6936f0d8a4..6f5872197d6c 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4843,8 +4843,15 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
>  	}
>  	brelse(iloc.bh);
>  	ext4_set_inode_flags(inode);
> -	if (ei->i_flags & EXT4_EA_INODE_FL)
> +
> +	if (ei->i_flags & EXT4_EA_INODE_FL) {
>  		ext4_xattr_inode_set_class(inode);
> +
> +		inode_lock(inode);
> +		inode->i_flags |= S_NOQUOTA;
> +		inode_unlock(inode);
> +	}
> +
>  	unlock_new_inode(inode);
>  	return inode;
>  
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index b02a23ec92ca..7d2b692d52ea 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -927,6 +927,10 @@ static void ext4_put_super(struct super_block *sb)
>  		invalidate_bdev(sbi->journal_bdev);
>  		ext4_blkdev_remove(sbi);
>  	}
> +	if (sbi->s_ea_inode_cache) {
> +		ext4_xattr_destroy_cache(sbi->s_ea_inode_cache);
> +		sbi->s_ea_inode_cache = NULL;
> +	}
>  	if (sbi->s_mb_cache) {
>  		ext4_xattr_destroy_cache(sbi->s_mb_cache);
>  		sbi->s_mb_cache = NULL;
> @@ -1178,7 +1182,10 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  	if (res)
>  		return res;
>  retry:
> -	credits = ext4_xattr_set_credits(inode, len);
> +	res = ext4_xattr_set_credits(inode, len, &credits);
> +	if (res)
> +		return res;
> +
>  	handle = ext4_journal_start(inode, EXT4_HT_MISC, credits);
>  	if (IS_ERR(handle))
>  		return PTR_ERR(handle);
> @@ -4067,6 +4074,15 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  		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 an s_ea_inode_cache");
> +			goto failed_mount_wq;
> +		}
> +	}
> +
>  	if ((DUMMY_ENCRYPTION_ENABLED(sbi) || ext4_has_feature_encrypt(sb)) &&
>  	    (blocksize != PAGE_SIZE)) {
>  		ext4_msg(sb, KERN_ERR,
> @@ -4296,6 +4312,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	if (EXT4_SB(sb)->rsv_conversion_wq)
>  		destroy_workqueue(EXT4_SB(sb)->rsv_conversion_wq);
>  failed_mount_wq:
> +	if (sbi->s_ea_inode_cache) {
> +		ext4_xattr_destroy_cache(sbi->s_ea_inode_cache);
> +		sbi->s_ea_inode_cache = NULL;
> +	}
>  	if (sbi->s_mb_cache) {
>  		ext4_xattr_destroy_cache(sbi->s_mb_cache);
>  		sbi->s_mb_cache = NULL;
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 6acce1f689ab..caddc176a612 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -55,6 +55,7 @@
>  #include <linux/slab.h>
>  #include <linux/mbcache.h>
>  #include <linux/quotaops.h>
> +#include <linux/crc32c.h>
>  #include "ext4_jbd2.h"
>  #include "ext4.h"
>  #include "xattr.h"
> @@ -79,6 +80,7 @@ ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *,
>  			    struct mb_cache_entry **);
>  static void ext4_xattr_rehash(struct ext4_xattr_header *,
>  			      struct ext4_xattr_entry *);
> +static int ext4_xattr_read_ea_hash(struct inode *ea_inode, u32 *hash);
>  
>  static const struct xattr_handler * const ext4_xattr_handler_map[] = {
>  	[EXT4_XATTR_INDEX_USER]		     = &ext4_xattr_user_handler,
> @@ -105,13 +107,23 @@ const struct xattr_handler *ext4_xattr_handlers[] = {
>  	NULL
>  };
>  
> +#define EXT4_XATTR_SYSTEM_EA_INFO  "eai"
> +
>  #define EXT4_GET_MB_CACHE(inode)	(((struct ext4_sb_info *) \
>  				inode->i_sb->s_fs_info)->s_mb_cache)
>  
> +#define EA_INODE_CACHE(inode)	(((struct ext4_sb_info *) \
> +				inode->i_sb->s_fs_info)->s_ea_inode_cache)
> +
>  static int
>  ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
>  			struct inode *inode);
>  
> +static int ext4_xattr_inode_init(handle_t *handle, struct inode *ea_inode,
> +				 u32 hash);
> +static int ext4_xattr_update_ea_info(struct inode *ea_inode, int ref_change,
> +				     u64 *ref_return, u32 *hash);
> +
>  #ifdef CONFIG_LOCKDEP
>  void ext4_xattr_inode_set_class(struct inode *ea_inode)
>  {
> @@ -329,14 +341,6 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
>  		goto error;
>  	}
>  
> -	if (EXT4_XATTR_INODE_GET_PARENT(inode) != parent->i_ino ||
> -	    inode->i_generation != parent->i_generation) {
> -		ext4_error(parent->i_sb, "Backpointer from EA inode %lu "
> -			   "to parent is invalid.", ea_ino);
> -		err = -EINVAL;
> -		goto error;
> -	}
> -
>  	if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
>  		ext4_error(parent->i_sb, "EA inode %lu does not have "
>  			   "EXT4_EA_INODE_FL flag set.\n", ea_ino);
> @@ -351,6 +355,11 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
>  	return err;
>  }
>  
> +static u32 ext4_xattr_inode_hash(const void *buffer, size_t size)
> +{
> +	return crc32c(0, buffer, size);

The metadata checksumming code uses crypto_alloc_shash to dynamically
bind to the crc32c implementation only when ext4 actually needs it.
This introduces a static module dependency on libcrc32c even though we
only need it if we're deduplicating xattrs, which is done only when
EXT4_FEATURE_INCOMPAT_EA_INODE is enabled, correct?

Or, looking through the code, maybe not; are we now capable of deduping
for any filesystem?

Anyway, if this dedupe feature is hidden behind INCOMPAT_EA_INODE then
this crc32c call binding should be done dynamically; however, if it
works for any filesystem and is therefore on all the time, the existing
users ought to be converted to use libcrc32c.

--D

> +}
> +
>  /*
>   * Read the value from the EA inode.
>   */
> @@ -358,17 +367,52 @@ static int
>  ext4_xattr_inode_get(struct inode *inode, unsigned long ea_ino, void *buffer,
>  		     size_t size)
>  {
> +	struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
>  	struct inode *ea_inode;
> -	int ret;
> +	u32 hash, calc_hash;
> +	struct mb_cache_entry *ce;
> +	int err;
>  
> -	ret = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> -	if (ret)
> -		return ret;
> +	err = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> +	if (err) {
> +		ea_inode = NULL;
> +		goto out;
> +	}
>  
> -	ret = ext4_xattr_inode_read(ea_inode, buffer, size);
> -	iput(ea_inode);
> +	if (i_size_read(ea_inode) != size) {
> +		ext4_warning_inode(ea_inode,
> +				   "ea_inode file size=%llu entry size=%zu",
> +				   i_size_read(ea_inode), size);
> +		err = -EFSCORRUPTED;
> +		goto out;
> +	}
>  
> -	return ret;
> +	err = ext4_xattr_inode_read(ea_inode, buffer, size);
> +	if (!err) {
> +		if (ext4_xattr_read_ea_hash(ea_inode, &hash))
> +			goto out;
> +
> +		/* Avoid hash calculation if already cached. */
> +		ce = mb_cache_entry_get(ea_inode_cache, hash, ea_inode->i_ino);
> +		if (ce) {
> +			mb_cache_entry_put(ea_inode_cache, ce);
> +			goto out;
> +		}
> +
> +		calc_hash = ext4_xattr_inode_hash(buffer, size);
> +		if (hash != calc_hash) {
> +			ext4_warning_inode(ea_inode, "EA inode saved hash=%#x "
> +					   "does not match calc_hash=%#x",
> +					   hash, calc_hash);
> +			goto out;
> +		}
> +
> +		mb_cache_entry_create(ea_inode_cache, GFP_NOFS, hash,
> +				      ea_inode->i_ino, true /* reusable */);
> +	}
> +out:
> +	iput(ea_inode);
> +	return err;
>  }
>  
>  static int
> @@ -657,6 +701,101 @@ static void ext4_xattr_update_super_block(handle_t *handle,
>  	}
>  }
>  
> +static inline size_t round_up_cluster(struct inode *inode, size_t length)
> +{
> +	struct super_block *sb = inode->i_sb;
> +	size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
> +				    inode->i_blkbits);
> +	size_t mask = ~(cluster_size - 1);
> +
> +	return (length + cluster_size - 1) & mask;
> +}
> +
> +static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
> +{
> +	int err;
> +
> +	err = dquot_alloc_inode(inode);
> +	if (err)
> +		return err;
> +	err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
> +	if (err)
> +		dquot_free_inode(inode);
> +	return err;
> +}
> +
> +static void ext4_xattr_inode_free_quota(struct inode *inode, size_t len)
> +{
> +	dquot_free_space_nodirty(inode, round_up_cluster(inode, len));
> +	dquot_free_inode(inode);
> +}
> +
> +static int __ext4_xattr_set_credits(struct super_block *sb,
> +				    struct buffer_head *block_bh,
> +				    size_t value_len)
> +{
> +	int credits;
> +	int blocks;
> +
> +	/*
> +	 * 1) Owner inode update
> +	 * 2) Ref count update on old xattr block
> +	 * 3) new xattr block
> +	 * 4) block bitmap update for new xattr block
> +	 * 5) group descriptor for new xattr block
> +	 */
> +	credits = 5;
> +
> +	/* We are done if ea_inode feature is not enabled. */
> +	if (!ext4_has_feature_ea_inode(sb))
> +		return credits;
> +
> +	/* New ea_inode, inode map, block bitmap, group descriptor. */
> +	credits += 4;
> +
> +	/* Data blocks. */
> +	blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
> +
> +	/* Indirection block. */
> +	blocks += 1;
> +
> +	/* Block bitmap and group descriptor updates for each block. */
> +	credits += blocks * 2;
> +
> +	/* Blocks themselves. */
> +	credits += blocks;
> +
> +	/* Dereference ea_inode holding old xattr value.
> +	 * Old ea_inode, inode map, block bitmap, group descriptor.
> +	 */
> +	credits += 4;
> +
> +	/* Data blocks for old ea_inode. */
> +	blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;
> +
> +	/* Indirection block for old ea_inode. */
> +	blocks += 1;
> +
> +	/* Block bitmap and group descriptor updates for each block. */
> +	credits += blocks * 2;
> +
> +	/* Quota updates. */
> +	credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);
> +
> +	/* We may need to clone the existing xattr block in which case we need
> +	 * to increment ref counts for existing ea_inodes referenced by it.
> +	 */
> +	if (block_bh) {
> +		struct ext4_xattr_entry *entry = BFIRST(block_bh);
> +
> +		for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
> +			if (entry->e_value_inum)
> +				/* Ref count update on ea_inode. */
> +				credits += 1;
> +	}
> +	return credits;
> +}
> +
>  int ext4_xattr_ensure_credits(handle_t *handle, struct inode *inode,
>  			      int credits, struct buffer_head *bh,
>  			      bool dirty, bool block_csum)
> @@ -706,12 +845,139 @@ int ext4_xattr_ensure_credits(handle_t *handle, struct inode *inode,
>  	return 0;
>  }
>  
> +static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
> +				       int ref_change)
> +{
> +	struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode);
> +	struct ext4_iloc iloc;
> +	s64 ref_return;
> +	u32 hash;
> +	int ret;
> +
> +	inode_lock(ea_inode);
> +
> +	ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
> +	if (ret) {
> +		iloc.bh = NULL;
> +		goto out;
> +	}
> +
> +	ret = ext4_xattr_update_ea_info(ea_inode, ref_change, &ref_return,
> +					&hash);
> +	if (ret)
> +		goto out;
> +
> +	if (ref_change > 0) {
> +		WARN_ONCE(ref_return <= 0, "EA inode %lu ref_return=%lld",
> +			  ea_inode->i_ino, ref_return);
> +
> +		if (ref_return == 1) {
> +			WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
> +				  ea_inode->i_ino, ea_inode->i_nlink);
> +
> +			set_nlink(ea_inode, 1);
> +			ext4_orphan_del(handle, ea_inode);
> +
> +			mb_cache_entry_create(ea_inode_cache, GFP_NOFS, hash,
> +					      ea_inode->i_ino,
> +					      true /* reusable */);
> +		}
> +	} else {
> +		WARN_ONCE(ref_return < 0, "EA inode %lu ref_return=%lld",
> +			  ea_inode->i_ino, ref_return);
> +
> +		if (ref_return == 0) {
> +			WARN_ONCE(ea_inode->i_nlink != 1,
> +				  "EA inode %lu i_nlink=%u",
> +				  ea_inode->i_ino, ea_inode->i_nlink);
> +
> +			clear_nlink(ea_inode);
> +			ext4_orphan_add(handle, ea_inode);
> +
> +			mb_cache_entry_delete(ea_inode_cache, hash,
> +					      ea_inode->i_ino);
> +		}
> +	}
> +
> +	ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
> +	iloc.bh = NULL;
> +	if (ret)
> +		ext4_warning_inode(ea_inode,
> +				   "ext4_mark_iloc_dirty() failed ret=%d", ret);
> +out:
> +	brelse(iloc.bh);
> +	inode_unlock(ea_inode);
> +	return ret;
> +}
> +
> +static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
> +{
> +	return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
> +}
> +
> +static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
> +{
> +	return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
> +}
> +
> +static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
> +					struct ext4_xattr_entry *first)
> +{
> +	struct inode *ea_inode;
> +	struct ext4_xattr_entry *entry;
> +	struct ext4_xattr_entry *failed_entry;
> +	unsigned int ea_ino;
> +	int err, saved_err;
> +
> +	for (entry = first; !IS_LAST_ENTRY(entry);
> +	     entry = EXT4_XATTR_NEXT(entry)) {
> +		if (!entry->e_value_inum)
> +			continue;
> +		ea_ino = le32_to_cpu(entry->e_value_inum);
> +		err = ext4_xattr_inode_iget(parent, ea_ino, &ea_inode);
> +		if (err)
> +			goto cleanup;
> +		err = ext4_xattr_inode_inc_ref(handle, ea_inode);
> +		if (err) {
> +			ext4_warning_inode(ea_inode, "inc ref error %d", err);
> +			iput(ea_inode);
> +			goto cleanup;
> +		}
> +		iput(ea_inode);
> +	}
> +	return 0;
> +
> +cleanup:
> +	saved_err = err;
> +	failed_entry = entry;
> +
> +	for (entry = first; entry != failed_entry;
> +	     entry = EXT4_XATTR_NEXT(entry)) {
> +		if (!entry->e_value_inum)
> +			continue;
> +		ea_ino = le32_to_cpu(entry->e_value_inum);
> +		err = ext4_xattr_inode_iget(parent, ea_ino, &ea_inode);
> +		if (err) {
> +			ext4_warning(parent->i_sb,
> +				     "cleanup ea_ino %u iget error %d", ea_ino,
> +				     err);
> +			continue;
> +		}
> +		err = ext4_xattr_inode_dec_ref(handle, ea_inode);
> +		if (err)
> +			ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
> +					   err);
> +		iput(ea_inode);
> +	}
> +	return saved_err;
> +}
> +
>  static void
> -ext4_xattr_inode_remove_all(handle_t *handle, struct inode *parent,
> -			    struct buffer_head *bh,
> -			    struct ext4_xattr_entry *first, bool block_csum,
> -			    struct ext4_xattr_inode_array **ea_inode_array,
> -			    int extra_credits)
> +ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
> +			     struct buffer_head *bh,
> +			     struct ext4_xattr_entry *first, bool block_csum,
> +			     struct ext4_xattr_inode_array **ea_inode_array,
> +			     int extra_credits, bool skip_quota)
>  {
>  	struct inode *ea_inode;
>  	struct ext4_xattr_entry *entry;
> @@ -748,10 +1014,16 @@ ext4_xattr_inode_remove_all(handle_t *handle, struct inode *parent,
>  			continue;
>  		}
>  
> -		inode_lock(ea_inode);
> -		clear_nlink(ea_inode);
> -		ext4_orphan_add(handle, ea_inode);
> -		inode_unlock(ea_inode);
> +		err = ext4_xattr_inode_dec_ref(handle, ea_inode);
> +		if (err) {
> +			ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
> +					   err);
> +			continue;
> +		}
> +
> +		if (!skip_quota)
> +			ext4_xattr_inode_free_quota(parent,
> +					      le32_to_cpu(entry->e_value_size));
>  
>  		/*
>  		 * Forget about ea_inode within the same transaction that decrements the ref
> @@ -784,7 +1056,9 @@ ext4_xattr_inode_remove_all(handle_t *handle, struct inode *parent,
>   */
>  static void
>  ext4_xattr_release_block(handle_t *handle, struct inode *inode,
> -			 struct buffer_head *bh)
> +			 struct buffer_head *bh,
> +			 struct ext4_xattr_inode_array **ea_inode_array,
> +			 int extra_credits)
>  {
>  	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
>  	u32 hash, ref;
> @@ -807,6 +1081,14 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
>  		mb_cache_entry_delete(ext4_mb_cache, hash, bh->b_blocknr);
>  		get_bh(bh);
>  		unlock_buffer(bh);
> +
> +		if (ext4_has_feature_ea_inode(inode->i_sb))
> +			ext4_xattr_inode_dec_ref_all(handle, inode, bh,
> +						     BFIRST(bh),
> +						     true /* block_csum */,
> +						     ea_inode_array,
> +						     extra_credits,
> +						     true /* skip_quota */);
>  		ext4_free_blocks(handle, inode, bh, 0, 1,
>  				 EXT4_FREE_BLOCKS_METADATA |
>  				 EXT4_FREE_BLOCKS_FORGET);
> @@ -947,7 +1229,7 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
>   * Create an inode to store the value of a large EA.
>   */
>  static struct inode *ext4_xattr_inode_create(handle_t *handle,
> -					     struct inode *inode)
> +					     struct inode *inode, u32 hash)
>  {
>  	struct inode *ea_inode = NULL;
>  	uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
> @@ -965,67 +1247,118 @@ static struct inode *ext4_xattr_inode_create(handle_t *handle,
>  		ea_inode->i_fop = &ext4_file_operations;
>  		ext4_set_aops(ea_inode);
>  		ext4_xattr_inode_set_class(ea_inode);
> -		ea_inode->i_generation = inode->i_generation;
> -		EXT4_I(ea_inode)->i_flags |= EXT4_EA_INODE_FL;
> -
> -		/*
> -		 * A back-pointer from EA inode to parent inode will be useful
> -		 * for e2fsck.
> -		 */
> -		EXT4_XATTR_INODE_SET_PARENT(ea_inode, inode->i_ino);
>  		unlock_new_inode(ea_inode);
>  		err = ext4_inode_attach_jinode(ea_inode);
> +		if (!err)
> +			err = ext4_xattr_inode_init(handle, ea_inode, hash);
>  		if (err) {
>  			iput(ea_inode);
>  			return ERR_PTR(err);
>  		}
> +
> +		/*
> +		 * Xattr inodes are shared therefore quota charging is performed
> +		 * at a higher level.
> +		 */
> +		dquot_free_inode(ea_inode);
> +		dquot_drop(ea_inode);
> +		inode_lock(ea_inode);
> +		ea_inode->i_flags |= S_NOQUOTA;
> +		inode_unlock(ea_inode);
>  	}
>  
>  	return ea_inode;
>  }
>  
> -/*
> - * Unlink the inode storing the value of the EA.
> - */
> -int ext4_xattr_inode_unlink(struct inode *inode, unsigned long ea_ino)
> +static struct inode *
> +ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
> +			    size_t value_len, u32 hash)
>  {
> -	struct inode *ea_inode = NULL;
> +	struct inode *ea_inode;
> +	struct mb_cache_entry *ce;
> +	struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
> +	void *ea_data = NULL;
>  	int err;
>  
> -	err = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> -	if (err)
> -		return err;
> +	ce = mb_cache_entry_find_first(ea_inode_cache, hash);
> +	while (ce) {
> +		ea_inode = ext4_iget(inode->i_sb, ce->e_value);
> +		if (IS_ERR(ea_inode)) {
> +			ea_inode = NULL;
> +			goto next;
> +		}
>  
> -	clear_nlink(ea_inode);
> -	iput(ea_inode);
> +		if (is_bad_inode(ea_inode) ||
> +		    !(EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) ||
> +		    i_size_read(ea_inode) != value_len)
> +			goto next;
>  
> -	return 0;
> +		if (!ea_data)
> +			ea_data = ext4_kvmalloc(value_len, GFP_NOFS);
> +
> +		if (!ea_data) {
> +			iput(ea_inode);
> +			return NULL;
> +		}
> +
> +		err = ext4_xattr_inode_read(ea_inode, ea_data, value_len);
> +		if (unlikely(err))
> +			goto next;
> +
> +		if (!memcmp(value, ea_data, value_len)) {
> +			mb_cache_entry_touch(ea_inode_cache, ce);
> +			mb_cache_entry_put(ea_inode_cache, ce);
> +			kvfree(ea_data);
> +			return ea_inode;
> +		}
> +	next:
> +		iput(ea_inode);
> +		ce = mb_cache_entry_find_next(ea_inode_cache, ce);
> +	}
> +	kvfree(ea_data);
> +	return NULL;
>  }
>  
>  /*
>   * Add value of the EA in an inode.
>   */
> -static int ext4_xattr_inode_set(handle_t *handle, struct inode *inode,
> -				unsigned long *ea_ino, const void *value,
> -				size_t value_len)
> +static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
> +					  const void *value, size_t value_len,
> +					  struct inode **ret_inode)
>  {
> +	u32 hash = ext4_xattr_inode_hash(value, value_len);
>  	struct inode *ea_inode;
>  	int err;
>  
> +	ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
> +	if (ea_inode) {
> +		err = ext4_xattr_inode_inc_ref(handle, ea_inode);
> +		if (err) {
> +			iput(ea_inode);
> +			return err;
> +		}
> +
> +		*ret_inode = ea_inode;
> +		return 0;
> +	}
> +
>  	/* Create an inode for the EA value */
> -	ea_inode = ext4_xattr_inode_create(handle, inode);
> +	ea_inode = ext4_xattr_inode_create(handle, inode, hash);
>  	if (IS_ERR(ea_inode))
>  		return PTR_ERR(ea_inode);
>  
>  	err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
> -	if (err)
> -		clear_nlink(ea_inode);
> -	else
> -		*ea_ino = ea_inode->i_ino;
> +	if (err) {
> +		ext4_xattr_inode_dec_ref(handle, ea_inode);
> +		iput(ea_inode);
> +		return err;
> +	}
>  
> -	iput(ea_inode);
> +	mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
> +			      ea_inode->i_ino, true /* reusable */);
>  
> -	return err;
> +	*ret_inode = ea_inode;
> +	return 0;
>  }
>  
>  static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
> @@ -1033,11 +1366,37 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
>  				handle_t *handle, struct inode *inode)
>  {
>  	struct ext4_xattr_entry *last;
> +	struct ext4_xattr_entry *here = s->here;
>  	size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
>  	int in_inode = i->in_inode;
> -	int rc;
> +	struct inode *old_ea_inode = NULL;
> +	struct inode *new_ea_inode = NULL;
> +	int ret;
>  
> -	/* Compute min_offs and last. */
> +	/*
> +	 * Optimization for the simple case when old and new values have the
> +	 * same padded sizes. Not applicable if the existing value is stored in
> +	 * an external inode.
> +	 */
> +	if (i->value && !s->not_found && !here->e_value_inum &&
> +	    EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) ==
> +	    EXT4_XATTR_SIZE(i->value_len)) {
> +		size_t offs = le16_to_cpu(here->e_value_offs);
> +		void *val = s->base + offs;
> +		size_t size = EXT4_XATTR_SIZE(i->value_len);
> +
> +		here->e_value_size = cpu_to_le32(i->value_len);
> +		if (i->value == EXT4_ZERO_XATTR_VALUE) {
> +			memset(val, 0, size);
> +		} else {
> +			memcpy(val, i->value, i->value_len);
> +			/* Clear padding bytes. */
> +			memset(val + i->value_len, 0, size - i->value_len);
> +		}
> +		return 0;
> +	}
> +
> +	/* Find out min_offs and last to calculate the free space. */
>  	last = s->first;
>  	for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
>  		if (!last->e_value_inum && last->e_value_size) {
> @@ -1048,120 +1407,149 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
>  	}
>  	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
>  	if (!s->not_found) {
> -		if (!in_inode &&
> -		    !s->here->e_value_inum && s->here->e_value_size) {
> -			size_t size = le32_to_cpu(s->here->e_value_size);
> +		if (!here->e_value_inum && here->e_value_size) {
> +			size_t size = le32_to_cpu(here->e_value_size);
>  			free += EXT4_XATTR_SIZE(size);
>  		}
>  		free += EXT4_XATTR_LEN(name_len);
>  	}
>  	if (i->value) {
> -		size_t value_len = EXT4_XATTR_SIZE(i->value_len);
> +		size_t value_len = in_inode ? 0 : EXT4_XATTR_SIZE(i->value_len);
>  
> -		if (in_inode)
> -			value_len = 0;
> +		if (free < EXT4_XATTR_LEN(name_len) + value_len) {
> +			ret = -ENOSPC;
> +			goto out;
> +		}
> +	}
>  
> -		if (free < EXT4_XATTR_LEN(name_len) + value_len)
> -			return -ENOSPC;
> +	/*
> +	 * Getting access to old and new ea inodes is subject to failures.
> +	 * Finish that work before doing any modifications to the xattr data.
> +	 */
> +	if (!s->not_found && here->e_value_inum) {
> +		ret = ext4_xattr_inode_iget(inode,
> +		 			    le32_to_cpu(here->e_value_inum),
> +		 			    &old_ea_inode);
> +		if (ret) {
> +			old_ea_inode = NULL;
> +			goto out;
> +		}
>  	}
> +	if (i->value && in_inode) {
> +		WARN_ON_ONCE(!i->value_len);
>  
> -	if (i->value && s->not_found) {
> -		/* Insert the new name. */
> -		size_t size = EXT4_XATTR_LEN(name_len);
> -		size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
> -		memmove((void *)s->here + size, s->here, rest);
> -		memset(s->here, 0, size);
> -		s->here->e_name_index = i->name_index;
> -		s->here->e_name_len = name_len;
> -		memcpy(s->here->e_name, i->name, name_len);
> -	} else {
> -		if (!s->here->e_value_inum && s->here->e_value_size &&
> -		    s->here->e_value_offs > 0) {
> -			void *first_val = s->base + min_offs;
> -			size_t offs = le16_to_cpu(s->here->e_value_offs);
> -			void *val = s->base + offs;
> -			size_t size = EXT4_XATTR_SIZE(
> -				le32_to_cpu(s->here->e_value_size));
> -
> -			if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
> -				/* The old and the new value have the same
> -				   size. Just replace. */
> -				s->here->e_value_size =
> -					cpu_to_le32(i->value_len);
> -				if (i->value == EXT4_ZERO_XATTR_VALUE) {
> -					memset(val, 0, size);
> -				} else {
> -					/* Clear pad bytes first. */
> -					memset(val + size - EXT4_XATTR_PAD, 0,
> -					       EXT4_XATTR_PAD);
> -					memcpy(val, i->value, i->value_len);
> -				}
> -				return 0;
> -			}
> +		ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
> +		if (ret)
> +			goto out;
>  
> -			/* Remove the old value. */
> -			memmove(first_val + size, first_val, val - first_val);
> -			memset(first_val, 0, size);
> -			s->here->e_value_size = 0;
> -			s->here->e_value_offs = 0;
> -			min_offs += size;
> -
> -			/* Adjust all value offsets. */
> -			last = s->first;
> -			while (!IS_LAST_ENTRY(last)) {
> -				size_t o = le16_to_cpu(last->e_value_offs);
> -				if (!last->e_value_inum &&
> -				    last->e_value_size && o < offs)
> -					last->e_value_offs =
> -						cpu_to_le16(o + size);
> -				last = EXT4_XATTR_NEXT(last);
> -			}
> +		ret = ext4_xattr_inode_lookup_create(handle, inode, i->value,
> +						     i->value_len,
> +						     &new_ea_inode);
> +		if (ret) {
> +			new_ea_inode = NULL;
> +			ext4_xattr_inode_free_quota(inode, i->value_len);
> +			goto out;
>  		}
> -		if (s->here->e_value_inum) {
> -			ext4_xattr_inode_unlink(inode,
> -					    le32_to_cpu(s->here->e_value_inum));
> -			s->here->e_value_inum = 0;
> +	}
> +
> +	if (old_ea_inode) {
> +		/* We are ready to release ref count on the old_ea_inode. */
> +		ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
> +		if (ret) {
> +			/* Release newly required ref count on new_ea_inode. */
> +			if (new_ea_inode) {
> +				int err;
> +
> +				err = ext4_xattr_inode_dec_ref(handle,
> +							       new_ea_inode);
> +				if (err)
> +					ext4_warning_inode(new_ea_inode,
> +						  "dec ref new_ea_inode err=%d",
> +						  err);
> +				ext4_xattr_inode_free_quota(inode,
> +							    i->value_len);
> +			}
> +			goto out;
>  		}
> -		if (!i->value) {
> -			/* Remove the old name. */
> -			size_t size = EXT4_XATTR_LEN(name_len);
> -			last = ENTRY((void *)last - size);
> -			memmove(s->here, (void *)s->here + size,
> -				(void *)last - (void *)s->here + sizeof(__u32));
> -			memset(last, 0, size);
> +
> +		ext4_xattr_inode_free_quota(inode,
> +					    le32_to_cpu(here->e_value_size));
> +	}
> +
> +	/* No failures allowed past this point. */
> +
> +	if (!s->not_found && here->e_value_offs) {
> +		/* Remove the old value. */
> +		void *first_val = s->base + min_offs;
> +		size_t offs = le16_to_cpu(here->e_value_offs);
> +		void *val = s->base + offs;
> +		size_t size = EXT4_XATTR_SIZE(
> +			le32_to_cpu(here->e_value_size));
> +
> +		memmove(first_val + size, first_val, val - first_val);
> +		memset(first_val, 0, size);
> +		min_offs += size;
> +
> +		/* Adjust all value offsets. */
> +		last = s->first;
> +		while (!IS_LAST_ENTRY(last)) {
> +			size_t o = le16_to_cpu(last->e_value_offs);
> +			if (!last->e_value_inum &&
> +			    last->e_value_size && o < offs)
> +				last->e_value_offs =
> +					cpu_to_le16(o + size);
> +			last = EXT4_XATTR_NEXT(last);
>  		}
>  	}
>  
> +	if (!s->not_found && !i->value) {
> +		/* Remove old name. */
> +		size_t size = EXT4_XATTR_LEN(name_len);
> +		last = ENTRY((void *)last - size);
> +		memmove(here, (void *)here + size,
> +			(void *)last - (void *)here + sizeof(__u32));
> +		memset(last, 0, size);
> +	} else if (s->not_found && i->value) {
> +		/* Insert new name. */
> +		size_t size = EXT4_XATTR_LEN(name_len);
> +		size_t rest = (void *)last - (void *)here + sizeof(__u32);
> +		memmove((void *)here + size, here, rest);
> +		memset(here, 0, size);
> +		here->e_name_index = i->name_index;
> +		here->e_name_len = name_len;
> +		memcpy(here->e_name, i->name, name_len);
> +	} else {
> +		WARN_ON_ONCE(s->not_found || !i->value);
> +		/* This is an update, reset value info. */
> +		here->e_value_inum = 0;
> +		here->e_value_offs = 0;
> +		here->e_value_size = 0;
> +	}
> +
>  	if (i->value) {
> -		/* Insert the new value. */
> +		/* Insert new value. */
>  		if (in_inode) {
> -			unsigned long ea_ino =
> -				le32_to_cpu(s->here->e_value_inum);
> -			rc = ext4_xattr_inode_set(handle, inode, &ea_ino,
> -						  i->value, i->value_len);
> -			if (rc)
> -				goto out;
> -			s->here->e_value_inum = cpu_to_le32(ea_ino);
> -			s->here->e_value_offs = 0;
> +			here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
>  		} else if (i->value_len) {
>  			size_t size = EXT4_XATTR_SIZE(i->value_len);
>  			void *val = s->base + min_offs - size;
> -			s->here->e_value_offs = cpu_to_le16(min_offs - size);
> -			s->here->e_value_inum = 0;
> +			here->e_value_offs = cpu_to_le16(min_offs - size);
>  			if (i->value == EXT4_ZERO_XATTR_VALUE) {
>  				memset(val, 0, size);
>  			} else {
> -				/* Clear the pad bytes first. */
> -				memset(val + size - EXT4_XATTR_PAD, 0,
> -				       EXT4_XATTR_PAD);
>  				memcpy(val, i->value, i->value_len);
> +				/* Clear padding bytes. */
> +				memset(val + i->value_len, 0,
> +				       size - i->value_len);
>  			}
>  		}
> -		s->here->e_value_size = cpu_to_le32(i->value_len);
> +		here->e_value_size = cpu_to_le32(i->value_len);
>  	}
> -
> +	ret = 0;
>  out:
> -	return rc;
> +	iput(old_ea_inode);
> +	iput(new_ea_inode);
> +	return ret;
>  }
>  
>  struct ext4_xattr_block_find {
> @@ -1223,6 +1611,8 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  	struct mb_cache_entry *ce = NULL;
>  	int error = 0;
>  	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
> +	struct inode *ea_inode = NULL;
> +	size_t old_ea_inode_size = 0;
>  
>  #define header(x) ((struct ext4_xattr_header *)(x))
>  
> @@ -1277,6 +1667,24 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  			header(s->base)->h_refcount = cpu_to_le32(1);
>  			s->here = ENTRY(s->base + offset);
>  			s->end = s->base + bs->bh->b_size;
> +
> +			/*
> +			 * If existing entry points to an xattr inode, we need
> +			 * to prevent ext4_xattr_set_entry() from decrementing
> +			 * ref count on it because the reference belongs to the
> +			 * original block. In this case, make the entry look
> +			 * like it has an empty value.
> +			 */
> +			if (!s->not_found && s->here->e_value_inum) {
> +				/*
> +				 * Defer quota free call for previous inode
> +				 * until success is guaranteed.
> +				 */
> +				old_ea_inode_size = le32_to_cpu(
> +							s->here->e_value_size);
> +				s->here->e_value_inum = 0;
> +				s->here->e_value_size = 0;
> +			}
>  		}
>  	} else {
>  		/* Allocate a buffer where we construct the new block. */
> @@ -1298,6 +1706,24 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  		goto bad_block;
>  	if (error)
>  		goto cleanup;
> +
> +	if (i->value && s->here->e_value_inum) {
> +		unsigned int ea_ino;
> +
> +		/*
> +		 * A ref count on ea_inode has been taken as part of the call to
> +		 * ext4_xattr_set_entry() above. We would like to drop this
> +		 * extra ref but we have to wait until the xattr block is
> +		 * initialized and has its own ref count on the ea_inode.
> +		 */
> +		ea_ino = le32_to_cpu(s->here->e_value_inum);
> +		error = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> +		if (error) {
> +			ea_inode = NULL;
> +			goto cleanup;
> +		}
> +	}
> +
>  	if (!IS_LAST_ENTRY(s->first))
>  		ext4_xattr_rehash(header(s->base), s->here);
>  
> @@ -1408,6 +1834,22 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  						 EXT4_FREE_BLOCKS_METADATA);
>  				goto cleanup;
>  			}
> +			error = ext4_xattr_inode_inc_ref_all(handle, inode,
> +						      ENTRY(header(s->base)+1));
> +			if (error)
> +				goto getblk_failed;
> +			if (ea_inode) {
> +				/* Drop the extra ref on ea_inode. */
> +				error = ext4_xattr_inode_dec_ref(handle,
> +								 ea_inode);
> +				if (error)
> +					ext4_warning_inode(ea_inode,
> +							   "dec ref error=%d",
> +							   error);
> +				iput(ea_inode);
> +				ea_inode = NULL;
> +			}
> +
>  			lock_buffer(new_bh);
>  			error = ext4_journal_get_create_access(handle, new_bh);
>  			if (error) {
> @@ -1427,15 +1869,36 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  		}
>  	}
>  
> +	if (old_ea_inode_size)
> +		ext4_xattr_inode_free_quota(inode, old_ea_inode_size);
> +
>  	/* Update the inode. */
>  	EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
>  
>  	/* Drop the previous xattr block. */
> -	if (bs->bh && bs->bh != new_bh)
> -		ext4_xattr_release_block(handle, inode, bs->bh);
> +	if (bs->bh && bs->bh != new_bh) {
> +		struct ext4_xattr_inode_array *ea_inode_array = NULL;
> +		ext4_xattr_release_block(handle, inode, bs->bh,
> +					 &ea_inode_array,
> +					 0 /* extra_credits */);
> +		ext4_xattr_inode_array_free(ea_inode_array);
> +	}
>  	error = 0;
>  
>  cleanup:
> +	if (ea_inode) {
> +		int error2;
> +		error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
> +		if (error2)
> +			ext4_warning_inode(ea_inode, "dec ref error=%d",
> +					   error2);
> +
> +		/* If there was an error, revert the quota charge. */
> +		if (error)
> +			ext4_xattr_inode_free_quota(inode,
> +						    i_size_read(ea_inode));
> +		iput(ea_inode);
> +	}
>  	if (ce)
>  		mb_cache_entry_put(ext4_mb_cache, ce);
>  	brelse(new_bh);
> @@ -1546,6 +2009,117 @@ static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
>  	return 0;
>  }
>  
> +struct ext4_xattr_ea_info {
> +	__le64 ref_count;	/* number of xattr entry references */
> +	__le32 hash;		/* crc32c hash of xattr data */
> +	__le32 reserved;	/* reserved, must be 0 */
> +};
> +
> +static int ext4_xattr_inode_init(handle_t *handle, struct inode *ea_inode,
> +				 u32 hash)
> +{
> +	struct ext4_xattr_ea_info ea_info = {
> +		.ref_count = cpu_to_le64(1),
> +		.hash = cpu_to_le32(hash),
> +		.reserved = 0,
> +	};
> +	struct ext4_xattr_info i = {
> +                .name_index = EXT4_XATTR_INDEX_SYSTEM,
> +		.name = EXT4_XATTR_SYSTEM_EA_INFO,
> +		.value = &ea_info,
> +		.value_len = sizeof(ea_info),
> +	};
> +	struct ext4_xattr_ibody_find is = {
> +		.s = { .not_found = -ENODATA, },
> +	};
> +	int err;
> +
> +	err = ext4_get_inode_loc(ea_inode, &is.iloc);
> +	if (err)
> +		return err;
> +
> +	err = ext4_xattr_ibody_find(ea_inode, &i, &is);
> +	if (err)
> +		return err;
> +
> +	return ext4_xattr_ibody_set(handle, ea_inode, &i, &is);
> +}
> +
> +static int ext4_xattr_update_ea_info(struct inode *ea_inode, int ref_change,
> +				     u64 *ref_return, u32 *hash)
> +{
> +	struct ext4_xattr_ea_info ea_info;
> +	struct ext4_xattr_info i = {
> +                .name_index = EXT4_XATTR_INDEX_SYSTEM,
> +		.name = EXT4_XATTR_SYSTEM_EA_INFO,
> +		.value = &ea_info,
> +		.value_len = sizeof(ea_info),
> +	};
> +	struct ext4_xattr_ibody_find is = {
> +		.s = { .not_found = -ENODATA, },
> +	};
> +	int err;
> +
> +	err = ext4_get_inode_loc(ea_inode, &is.iloc);
> +	if (err)
> +		return err;
> +
> +	err = ext4_xattr_ibody_find(ea_inode, &i, &is);
> +	if (err)
> +		return err;
> +
> +	if (WARN_ON(is.s.not_found) ||
> +	    WARN_ON(le32_to_cpu(is.s.here->e_value_size) != sizeof(ea_info)))
> +		return -EFSCORRUPTED;
> +
> +	memcpy(&ea_info,
> +	       ((void *)is.s.base) + le16_to_cpu(is.s.here->e_value_offs),
> +	       sizeof(ea_info));
> +
> +	if (hash)
> +		*hash = le32_to_cpu(ea_info.hash);
> +
> +	*ref_return = le64_to_cpu(ea_info.ref_count) + ref_change;
> +	ea_info.ref_count = cpu_to_le64(*ref_return);
> +
> +	return ext4_xattr_set_entry(&i, &is.s, NULL, ea_inode);
> +}
> +
> +static int ext4_xattr_read_ea_hash(struct inode *ea_inode, u32 *hash)
> +{
> +	struct ext4_xattr_info i = {
> +                .name_index = EXT4_XATTR_INDEX_SYSTEM,
> +		.name = EXT4_XATTR_SYSTEM_EA_INFO,
> +	};
> +	struct ext4_xattr_ibody_find is = {
> +		.s = { .not_found = -ENODATA, },
> +	};
> +	struct ext4_xattr_ea_info *ea_info;
> +	void *ptr;
> +	int err;
> +
> +	err = ext4_get_inode_loc(ea_inode, &is.iloc);
> +	if (err)
> +		return err;
> +
> +	err = ext4_xattr_ibody_find(ea_inode, &i, &is);
> +	if (err)
> +		return err;
> +
> +	if (WARN_ON(is.s.not_found) ||
> +	    WARN_ON(le32_to_cpu(is.s.here->e_value_size) != sizeof(*ea_info)))
> +		return -EFSCORRUPTED;
> +
> +	ptr = ((void *)is.s.base) + le16_to_cpu(is.s.here->e_value_offs);
> +	ea_info = (struct ext4_xattr_ea_info *)ptr;
> +
> +	if (WARN_ON(ea_info->reserved != 0))
> +		return -EFSCORRUPTED;
> +
> +	*hash = le32_to_cpu(ea_info->hash);
> +	return 0;
> +}
> +
>  static int ext4_xattr_value_same(struct ext4_xattr_search *s,
>  				 struct ext4_xattr_info *i)
>  {
> @@ -1560,6 +2134,22 @@ static int ext4_xattr_value_same(struct ext4_xattr_search *s,
>  	return !memcmp(value, i->value, i->value_len);
>  }
>  
> +struct buffer_head *ext4_xattr_get_block(struct inode *inode)
> +{
> +	struct buffer_head *bh;
> +	int error;
> +
> +	if (!EXT4_I(inode)->i_file_acl)
> +		return NULL;
> +	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
> +	if (!bh)
> +		return ERR_PTR(-EIO);
> +	error = ext4_xattr_check_block(inode, bh);
> +	if (error)
> +		return ERR_PTR(error);
> +	return bh;
> +}
> +
>  /*
>   * ext4_xattr_set_handle()
>   *
> @@ -1602,9 +2192,18 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
>  
>  	/* Check journal credits under write lock. */
>  	if (ext4_handle_valid(handle)) {
> +		struct buffer_head *bh;
>  		int credits;
>  
> -		credits = ext4_xattr_set_credits(inode, value_len);
> +		bh = ext4_xattr_get_block(inode);
> +		if (IS_ERR(bh)) {
> +			error = PTR_ERR(bh);
> +			goto cleanup;
> +		}
> +
> +		credits = __ext4_xattr_set_credits(inode->i_sb, bh, value_len);
> +		brelse(bh);
> +
>  		if (!ext4_handle_has_enough_credits(handle, credits)) {
>  			error = -ENOSPC;
>  			goto cleanup;
> @@ -1640,6 +2239,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
>  		if (flags & XATTR_CREATE)
>  			goto cleanup;
>  	}
> +
>  	if (!value) {
>  		if (!is.s.not_found)
>  			error = ext4_xattr_ibody_set(handle, inode, &i, &is);
> @@ -1708,34 +2308,29 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
>  	return error;
>  }
>  
> -int ext4_xattr_set_credits(struct inode *inode, size_t value_len)
> +int ext4_xattr_set_credits(struct inode *inode, size_t value_len, int *credits)
>  {
> -	struct super_block *sb = inode->i_sb;
> -	int credits;
> -
> -	if (!EXT4_SB(sb)->s_journal)
> -		return 0;
> -
> -	credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb);
> +	struct buffer_head *bh;
> +	int err;
>  
> -	/*
> -	 * In case of inline data, we may push out the data to a block,
> -	 * so we need to reserve credits for this eventuality
> -	 */
> -	if (ext4_has_inline_data(inode))
> -	        credits += ext4_writepage_trans_blocks(inode) + 1;
> +	*credits = 0;
>  
> -	if (ext4_has_feature_ea_inode(sb)) {
> -		int nrblocks = (value_len + sb->s_blocksize - 1) >>
> -					sb->s_blocksize_bits;
> +	if (!EXT4_SB(inode->i_sb)->s_journal)
> +		return 0;
>  
> -		/* For new inode */
> -		credits += EXT4_SINGLEDATA_TRANS_BLOCKS(sb) + 3;
> +	down_read(&EXT4_I(inode)->xattr_sem);
>  
> -		/* For data blocks of EA inode */
> -		credits += ext4_meta_trans_blocks(inode, nrblocks, 0);
> +	bh = ext4_xattr_get_block(inode);
> +	if (IS_ERR(bh)) {
> +		err = PTR_ERR(bh);
> +	} else {
> +		*credits = __ext4_xattr_set_credits(inode->i_sb, bh, value_len);
> +		brelse(bh);
> +		err = 0;
>  	}
> -	return credits;
> +
> +	up_read(&EXT4_I(inode)->xattr_sem);
> +	return err;
>  }
>  
>  /*
> @@ -1760,7 +2355,10 @@ ext4_xattr_set(struct inode *inode, int name_index, const char *name,
>  		return error;
>  
>  retry:
> -	credits = ext4_xattr_set_credits(inode, value_len);
> +	error = ext4_xattr_set_credits(inode, value_len, &credits);
> +	if (error)
> +		return error;
> +
>  	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
>  	if (IS_ERR(handle)) {
>  		error = PTR_ERR(handle);
> @@ -2066,10 +2664,10 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
>  	return error;
>  }
>  
> -
>  #define EIA_INCR 16 /* must be 2^n */
>  #define EIA_MASK (EIA_INCR - 1)
> -/* Add the large xattr @inode into @ea_inode_array for later deletion.
> +
> +/* Add the large xattr @inode into @ea_inode_array for deferred iput().
>   * If @ea_inode_array is new or full it will be grown and the old
>   * contents copied over.
>   */
> @@ -2114,21 +2712,19 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
>   * ext4_xattr_delete_inode()
>   *
>   * Free extended attribute resources associated with this inode. Traverse
> - * all entries and unlink any xattr inodes associated with this inode. This
> - * is called immediately before an inode is freed. We have exclusive
> - * access to the inode. If an orphan inode is deleted it will also delete any
> - * xattr block and all xattr inodes. They are checked by ext4_xattr_inode_iget()
> - * to ensure they belong to the parent inode and were not deleted already.
> + * all entries and decrement reference on any xattr inodes associated with this
> + * inode. This is called immediately before an inode is freed. We have exclusive
> + * access to the inode. If an orphan inode is deleted it will also release its
> + * references on xattr block and xattr inodes.
>   */
> -int
> -ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> -			struct ext4_xattr_inode_array **ea_inode_array,
> -			int extra_credits)
> +int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> +			    struct ext4_xattr_inode_array **ea_inode_array,
> +			    int extra_credits)
>  {
>  	struct buffer_head *bh = NULL;
>  	struct ext4_xattr_ibody_header *header;
> -	struct ext4_inode *raw_inode;
>  	struct ext4_iloc iloc = { .bh = NULL };
> +	struct ext4_xattr_entry *entry;
>  	int error;
>  
>  	error = ext4_xattr_ensure_credits(handle, inode, extra_credits,
> @@ -2140,66 +2736,71 @@ ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
>  		goto cleanup;
>  	}
>  
> -	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
> -		goto delete_external_ea;
> -
> -	error = ext4_get_inode_loc(inode, &iloc);
> -	if (error)
> -		goto cleanup;
> +	if (ext4_has_feature_ea_inode(inode->i_sb) &&
> +	    ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
>  
> -	error = ext4_journal_get_write_access(handle, iloc.bh);
> -	if (error)
> -		goto cleanup;
> +		error = ext4_get_inode_loc(inode, &iloc);
> +		if (error) {
> +			EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
> +			goto cleanup;
> +		}
>  
> -	raw_inode = ext4_raw_inode(&iloc);
> -	header = IHDR(inode, raw_inode);
> -	ext4_xattr_inode_remove_all(handle, inode, iloc.bh, IFIRST(header),
> -				    false /* block_csum */, ea_inode_array,
> -				    extra_credits);
> +		error = ext4_journal_get_write_access(handle, iloc.bh);
> +		if (error) {
> +			EXT4_ERROR_INODE(inode, "write access (error %d)",
> +					 error);
> +			goto cleanup;
> +		}
>  
> -delete_external_ea:
> -	if (!EXT4_I(inode)->i_file_acl) {
> -		error = 0;
> -		goto cleanup;
> -	}
> -	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
> -	if (!bh) {
> -		EXT4_ERROR_INODE(inode, "block %llu read error",
> -				 EXT4_I(inode)->i_file_acl);
> -		error = -EIO;
> -		goto cleanup;
> -	}
> -	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
> -	    BHDR(bh)->h_blocks != cpu_to_le32(1)) {
> -		EXT4_ERROR_INODE(inode, "bad block %llu",
> -				 EXT4_I(inode)->i_file_acl);
> -		error = -EFSCORRUPTED;
> -		goto cleanup;
> +		header = IHDR(inode, ext4_raw_inode(&iloc));
> +		if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
> +			ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
> +						     IFIRST(header),
> +						     false /* block_csum */,
> +						     ea_inode_array,
> +						     extra_credits,
> +						     false /* skip_quota */);
>  	}
>  
> -	if (ext4_has_feature_ea_inode(inode->i_sb)) {
> -		error = ext4_journal_get_write_access(handle, bh);
> -		if (error) {
> -			EXT4_ERROR_INODE(inode, "write access %llu",
> +	if (EXT4_I(inode)->i_file_acl) {
> +		bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
> +		if (!bh) {
> +			EXT4_ERROR_INODE(inode, "block %llu read error",
>  					 EXT4_I(inode)->i_file_acl);
> +			error = -EIO;
> +			goto cleanup;
> +		}
> +		error = ext4_xattr_check_block(inode, bh);
> +		if (error) {
> +			EXT4_ERROR_INODE(inode, "bad block %llu (error %d)",
> +					 EXT4_I(inode)->i_file_acl, error);
>  			goto cleanup;
>  		}
> -		ext4_xattr_inode_remove_all(handle, inode, bh,
> -					    BFIRST(bh),
> -					    true /* block_csum */,
> -					    ea_inode_array,
> -					    extra_credits);
> -	}
>  
> -	ext4_xattr_release_block(handle, inode, bh);
> -	/* Update i_file_acl within the same transaction that releases block. */
> -	EXT4_I(inode)->i_file_acl = 0;
> -	error = ext4_mark_inode_dirty(handle, inode);
> -	if (error) {
> -		EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
> -				 error);
> -		goto cleanup;
> +		if (ext4_has_feature_ea_inode(inode->i_sb)) {
> +			for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
> +			     entry = EXT4_XATTR_NEXT(entry))
> +				if (entry->e_value_inum)
> +					ext4_xattr_inode_free_quota(inode,
> +					      le32_to_cpu(entry->e_value_size));
> +
> +		}
> +
> +		ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
> +					 extra_credits);
> +		/*
> +		 * Update i_file_acl value in the same transaction that releases
> +		 * block.
> +		 */
> +		EXT4_I(inode)->i_file_acl = 0;
> +		error = ext4_mark_inode_dirty(handle, inode);
> +		if (error) {
> +			EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
> +					 error);
> +			goto cleanup;
> +		}
>  	}
> +	error = 0;
>  cleanup:
>  	brelse(iloc.bh);
>  	brelse(bh);
> @@ -2208,17 +2809,13 @@ ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
>  
>  void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
>  {
> -	struct inode	*ea_inode;
> -	int		idx = 0;
> +	int idx;
>  
>  	if (ea_inode_array == NULL)
>  		return;
>  
> -	for (; idx < ea_inode_array->count; ++idx) {
> -		ea_inode = ea_inode_array->inodes[idx];
> -		clear_nlink(ea_inode);
> -		iput(ea_inode);
> -	}
> +	for (idx = 0; idx < ea_inode_array->count; ++idx)
> +		iput(ea_inode_array->inodes[idx]);
>  	kfree(ea_inode_array);
>  }
>  
> diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
> index b2005a2716d9..67616cb9a059 100644
> --- a/fs/ext4/xattr.h
> +++ b/fs/ext4/xattr.h
> @@ -70,19 +70,6 @@ struct ext4_xattr_entry {
>  #define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
>  
>  /*
> - * Link EA inode back to parent one using i_mtime field.
> - * Extra integer type conversion added to ignore higher
> - * bits in i_mtime.tv_sec which might be set by ext4_get()
> - */
> -#define EXT4_XATTR_INODE_SET_PARENT(inode, inum)      \
> -do {                                                  \
> -      (inode)->i_mtime.tv_sec = inum;                 \
> -} while(0)
> -
> -#define EXT4_XATTR_INODE_GET_PARENT(inode)            \
> -((__u32)(inode)->i_mtime.tv_sec)
> -
> -/*
>   * The minimum size of EA value when you start storing it in an external inode
>   * size of block - size of header - size of 1 entry - 4 null bytes
>  */
> @@ -165,9 +152,9 @@ extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
>  extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
>  extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
>  extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
> -extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len);
> +extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
> +				  int *credits);
>  
> -extern int ext4_xattr_inode_unlink(struct inode *inode, unsigned long ea_ino);
>  extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
>  				   struct ext4_xattr_inode_array **array,
>  				   int extra_credits);
> diff --git a/fs/mbcache.c b/fs/mbcache.c
> index 77a5b99d8f92..7dfdca822ccb 100644
> --- a/fs/mbcache.c
> +++ b/fs/mbcache.c
> @@ -13,10 +13,11 @@
>   * mb_cache_entry_delete()).
>   *
>   * Ext2 and ext4 use this cache for deduplication of extended attribute blocks.
> - * They use hash of a block contents as a key and block number as a value.
> - * That's why keys need not be unique (different xattr blocks may end up having
> - * the same hash). However block number always uniquely identifies a cache
> - * entry.
> + * Ext4 also uses it for deduplication of xattr values stored in inodes.
> + * They use hash of data as a key and provide a value that may represent a
> + * block or inode number. That's why keys need not be unique (hash of different
> + * data may be the same). However user provided value always uniquely
> + * identifies a cache entry.
>   *
>   * We provide functions for creation and removal of entries, search by key,
>   * and a special "delete entry with given key-value pair" operation. Fixed
> -- 
> 2.13.0.219.gdb65acc882-goog
> 




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