xattr.c 34.3 KB
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/*
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 * linux/fs/ext4/xattr.c
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 *
 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
 *
 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
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 * Ext4 code with a lot of help from Eric Jarman <ejarman@acm.org>.
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 * Extended attributes for symlinks and special files added per
 *  suggestion of Luka Renko <luka.renko@hermes.si>.
 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
 *  Red Hat Inc.
 * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
 *  and Andreas Gruenbacher <agruen@suse.de>.
 */

/*
 * Extended attributes are stored directly in inodes (on file systems with
 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
 * field contains the block number if an inode uses an additional block. All
 * attributes must fit in the inode and one additional block. Blocks that
 * contain the identical set of attributes may be shared among several inodes.
 * Identical blocks are detected by keeping a cache of blocks that have
 * recently been accessed.
 *
 * The attributes in inodes and on blocks have a different header; the entries
 * are stored in the same format:
 *
 *   +------------------+
 *   | header           |
 *   | entry 1          | |
 *   | entry 2          | | growing downwards
 *   | entry 3          | v
 *   | four null bytes  |
 *   | . . .            |
 *   | value 1          | ^
 *   | value 3          | | growing upwards
 *   | value 2          | |
 *   +------------------+
 *
 * The header is followed by multiple entry descriptors. In disk blocks, the
 * entry descriptors are kept sorted. In inodes, they are unsorted. The
 * attribute values are aligned to the end of the block in no specific order.
 *
 * Locking strategy
 * ----------------
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 * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.
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 * EA blocks are only changed if they are exclusive to an inode, so
 * holding xattr_sem also means that nothing but the EA block's reference
 * count can change. Multiple writers to the same block are synchronized
 * by the buffer lock.
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
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#include <linux/ext4_jbd2.h>
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#include <linux/ext4_fs.h>
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#include <linux/mbcache.h>
#include <linux/quotaops.h>
#include <linux/rwsem.h>
#include "xattr.h"
#include "acl.h"

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#define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
#define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
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#define BFIRST(bh) ENTRY(BHDR(bh)+1)
#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)

#define IHDR(inode, raw_inode) \
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	((struct ext4_xattr_ibody_header *) \
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		((void *)raw_inode + \
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		 EXT4_GOOD_OLD_INODE_SIZE + \
		 EXT4_I(inode)->i_extra_isize))
#define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
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#ifdef EXT4_XATTR_DEBUG
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# define ea_idebug(inode, f...) do { \
		printk(KERN_DEBUG "inode %s:%lu: ", \
			inode->i_sb->s_id, inode->i_ino); \
		printk(f); \
		printk("\n"); \
	} while (0)
# define ea_bdebug(bh, f...) do { \
		char b[BDEVNAME_SIZE]; \
		printk(KERN_DEBUG "block %s:%lu: ", \
			bdevname(bh->b_bdev, b), \
			(unsigned long) bh->b_blocknr); \
		printk(f); \
		printk("\n"); \
	} while (0)
#else
# define ea_idebug(f...)
# define ea_bdebug(f...)
#endif

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static void ext4_xattr_cache_insert(struct buffer_head *);
static struct buffer_head *ext4_xattr_cache_find(struct inode *,
						 struct ext4_xattr_header *,
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						 struct mb_cache_entry **);
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static void ext4_xattr_rehash(struct ext4_xattr_header *,
			      struct ext4_xattr_entry *);
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static struct mb_cache *ext4_xattr_cache;
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static struct xattr_handler *ext4_xattr_handler_map[] = {
	[EXT4_XATTR_INDEX_USER]		     = &ext4_xattr_user_handler,
#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
	[EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
	[EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
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#endif
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	[EXT4_XATTR_INDEX_TRUSTED]	     = &ext4_xattr_trusted_handler,
#ifdef CONFIG_EXT4DEV_FS_SECURITY
	[EXT4_XATTR_INDEX_SECURITY]	     = &ext4_xattr_security_handler,
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#endif
};

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struct xattr_handler *ext4_xattr_handlers[] = {
	&ext4_xattr_user_handler,
	&ext4_xattr_trusted_handler,
#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
	&ext4_xattr_acl_access_handler,
	&ext4_xattr_acl_default_handler,
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#endif
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#ifdef CONFIG_EXT4DEV_FS_SECURITY
	&ext4_xattr_security_handler,
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#endif
	NULL
};

static inline struct xattr_handler *
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ext4_xattr_handler(int name_index)
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{
	struct xattr_handler *handler = NULL;

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	if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
		handler = ext4_xattr_handler_map[name_index];
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	return handler;
}

/*
 * Inode operation listxattr()
 *
 * dentry->d_inode->i_mutex: don't care
 */
ssize_t
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ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
147
{
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	return ext4_xattr_list(dentry->d_inode, buffer, size);
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}

static int
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ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
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{
	while (!IS_LAST_ENTRY(entry)) {
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		struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
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		if ((void *)next >= end)
			return -EIO;
		entry = next;
	}
	return 0;
}

static inline int
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ext4_xattr_check_block(struct buffer_head *bh)
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{
	int error;

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	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
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	    BHDR(bh)->h_blocks != cpu_to_le32(1))
		return -EIO;
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	error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
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	return error;
}

static inline int
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ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
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{
	size_t value_size = le32_to_cpu(entry->e_value_size);

	if (entry->e_value_block != 0 || value_size > size ||
	    le16_to_cpu(entry->e_value_offs) + value_size > size)
		return -EIO;
	return 0;
}

static int
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ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
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		      const char *name, size_t size, int sorted)
{
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	struct ext4_xattr_entry *entry;
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	size_t name_len;
	int cmp = 1;

	if (name == NULL)
		return -EINVAL;
	name_len = strlen(name);
	entry = *pentry;
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	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
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		cmp = name_index - entry->e_name_index;
		if (!cmp)
			cmp = name_len - entry->e_name_len;
		if (!cmp)
			cmp = memcmp(name, entry->e_name, name_len);
		if (cmp <= 0 && (sorted || cmp == 0))
			break;
	}
	*pentry = entry;
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	if (!cmp && ext4_xattr_check_entry(entry, size))
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			return -EIO;
	return cmp ? -ENODATA : 0;
}

static int
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ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
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		     void *buffer, size_t buffer_size)
{
	struct buffer_head *bh = NULL;
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	struct ext4_xattr_entry *entry;
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	size_t size;
	int error;

	ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
		  name_index, name, buffer, (long)buffer_size);

	error = -ENODATA;
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	if (!EXT4_I(inode)->i_file_acl)
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		goto cleanup;
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	ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
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	if (!bh)
		goto cleanup;
	ea_bdebug(bh, "b_count=%d, refcount=%d",
		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
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	if (ext4_xattr_check_block(bh)) {
bad_block:	ext4_error(inode->i_sb, __FUNCTION__,
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			   "inode %lu: bad block "E3FSBLK, inode->i_ino,
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			   EXT4_I(inode)->i_file_acl);
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		error = -EIO;
		goto cleanup;
	}
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	ext4_xattr_cache_insert(bh);
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	entry = BFIRST(bh);
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	error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
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	if (error == -EIO)
		goto bad_block;
	if (error)
		goto cleanup;
	size = le32_to_cpu(entry->e_value_size);
	if (buffer) {
		error = -ERANGE;
		if (size > buffer_size)
			goto cleanup;
		memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
		       size);
	}
	error = size;

cleanup:
	brelse(bh);
	return error;
}

static int
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ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
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		     void *buffer, size_t buffer_size)
{
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	struct ext4_xattr_ibody_header *header;
	struct ext4_xattr_entry *entry;
	struct ext4_inode *raw_inode;
	struct ext4_iloc iloc;
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	size_t size;
	void *end;
	int error;

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	if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
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		return -ENODATA;
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	error = ext4_get_inode_loc(inode, &iloc);
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	if (error)
		return error;
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	raw_inode = ext4_raw_inode(&iloc);
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	header = IHDR(inode, raw_inode);
	entry = IFIRST(header);
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	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
	error = ext4_xattr_check_names(entry, end);
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	if (error)
		goto cleanup;
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	error = ext4_xattr_find_entry(&entry, name_index, name,
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				      end - (void *)entry, 0);
	if (error)
		goto cleanup;
	size = le32_to_cpu(entry->e_value_size);
	if (buffer) {
		error = -ERANGE;
		if (size > buffer_size)
			goto cleanup;
		memcpy(buffer, (void *)IFIRST(header) +
		       le16_to_cpu(entry->e_value_offs), size);
	}
	error = size;

cleanup:
	brelse(iloc.bh);
	return error;
}

/*
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 * ext4_xattr_get()
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 *
 * Copy an extended attribute into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
int
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ext4_xattr_get(struct inode *inode, int name_index, const char *name,
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	       void *buffer, size_t buffer_size)
{
	int error;

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	down_read(&EXT4_I(inode)->xattr_sem);
	error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
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				     buffer_size);
	if (error == -ENODATA)
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		error = ext4_xattr_block_get(inode, name_index, name, buffer,
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					     buffer_size);
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	up_read(&EXT4_I(inode)->xattr_sem);
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	return error;
}

static int
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ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry,
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			char *buffer, size_t buffer_size)
{
	size_t rest = buffer_size;

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	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
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		struct xattr_handler *handler =
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			ext4_xattr_handler(entry->e_name_index);
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		if (handler) {
			size_t size = handler->list(inode, buffer, rest,
						    entry->e_name,
						    entry->e_name_len);
			if (buffer) {
				if (size > rest)
					return -ERANGE;
				buffer += size;
			}
			rest -= size;
		}
	}
	return buffer_size - rest;
}

static int
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ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
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{
	struct buffer_head *bh = NULL;
	int error;

	ea_idebug(inode, "buffer=%p, buffer_size=%ld",
		  buffer, (long)buffer_size);

	error = 0;
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	if (!EXT4_I(inode)->i_file_acl)
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		goto cleanup;
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	ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
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	error = -EIO;
	if (!bh)
		goto cleanup;
	ea_bdebug(bh, "b_count=%d, refcount=%d",
		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
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	if (ext4_xattr_check_block(bh)) {
		ext4_error(inode->i_sb, __FUNCTION__,
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			   "inode %lu: bad block "E3FSBLK, inode->i_ino,
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			   EXT4_I(inode)->i_file_acl);
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		error = -EIO;
		goto cleanup;
	}
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	ext4_xattr_cache_insert(bh);
	error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
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cleanup:
	brelse(bh);

	return error;
}

static int
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ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
394
{
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	struct ext4_xattr_ibody_header *header;
	struct ext4_inode *raw_inode;
	struct ext4_iloc iloc;
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	void *end;
	int error;

401
	if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
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		return 0;
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	error = ext4_get_inode_loc(inode, &iloc);
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	if (error)
		return error;
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	raw_inode = ext4_raw_inode(&iloc);
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	header = IHDR(inode, raw_inode);
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	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
	error = ext4_xattr_check_names(IFIRST(header), end);
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	if (error)
		goto cleanup;
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	error = ext4_xattr_list_entries(inode, IFIRST(header),
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					buffer, buffer_size);

cleanup:
	brelse(iloc.bh);
	return error;
}

/*
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 * ext4_xattr_list()
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 *
 * Copy a list of attribute names into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
int
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ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
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{
	int i_error, b_error;

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	down_read(&EXT4_I(inode)->xattr_sem);
	i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size);
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	if (i_error < 0) {
		b_error = 0;
	} else {
		if (buffer) {
			buffer += i_error;
			buffer_size -= i_error;
		}
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		b_error = ext4_xattr_block_list(inode, buffer, buffer_size);
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		if (b_error < 0)
			i_error = 0;
	}
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	up_read(&EXT4_I(inode)->xattr_sem);
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	return i_error + b_error;
}

/*
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 * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
454 455
 * not set, set it.
 */
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static void ext4_xattr_update_super_block(handle_t *handle,
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					  struct super_block *sb)
{
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	if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
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		return;

	lock_super(sb);
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	if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
		EXT4_SB(sb)->s_es->s_feature_compat |=
			cpu_to_le32(EXT4_FEATURE_COMPAT_EXT_ATTR);
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		sb->s_dirt = 1;
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		ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
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	}
	unlock_super(sb);
}

/*
 * Release the xattr block BH: If the reference count is > 1, decrement
 * it; otherwise free the block.
 */
static void
477
ext4_xattr_release_block(handle_t *handle, struct inode *inode,
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			 struct buffer_head *bh)
{
	struct mb_cache_entry *ce = NULL;

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	ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
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	if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
		ea_bdebug(bh, "refcount now=0; freeing");
		if (ce)
			mb_cache_entry_free(ce);
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		ext4_free_blocks(handle, inode, bh->b_blocknr, 1);
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		get_bh(bh);
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		ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
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	} else {
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		if (ext4_journal_get_write_access(handle, bh) == 0) {
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			lock_buffer(bh);
			BHDR(bh)->h_refcount = cpu_to_le32(
				le32_to_cpu(BHDR(bh)->h_refcount) - 1);
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			ext4_journal_dirty_metadata(handle, bh);
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			if (IS_SYNC(inode))
				handle->h_sync = 1;
			DQUOT_FREE_BLOCK(inode, 1);
			unlock_buffer(bh);
			ea_bdebug(bh, "refcount now=%d; releasing",
				  le32_to_cpu(BHDR(bh)->h_refcount));
		}
		if (ce)
			mb_cache_entry_release(ce);
	}
}

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struct ext4_xattr_info {
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	int name_index;
	const char *name;
	const void *value;
	size_t value_len;
};

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struct ext4_xattr_search {
	struct ext4_xattr_entry *first;
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	void *base;
	void *end;
519
	struct ext4_xattr_entry *here;
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	int not_found;
};

static int
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ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
525
{
526
	struct ext4_xattr_entry *last;
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	size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);

	/* Compute min_offs and last. */
	last = s->first;
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	for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
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		if (!last->e_value_block && last->e_value_size) {
			size_t offs = le16_to_cpu(last->e_value_offs);
			if (offs < min_offs)
				min_offs = offs;
		}
	}
	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
	if (!s->not_found) {
		if (!s->here->e_value_block && s->here->e_value_size) {
			size_t size = le32_to_cpu(s->here->e_value_size);
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			free += EXT4_XATTR_SIZE(size);
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		}
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		free += EXT4_XATTR_LEN(name_len);
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	}
	if (i->value) {
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		if (free < EXT4_XATTR_SIZE(i->value_len) ||
		    free < EXT4_XATTR_LEN(name_len) +
			   EXT4_XATTR_SIZE(i->value_len))
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			return -ENOSPC;
	}

	if (i->value && s->not_found) {
		/* Insert the new name. */
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		size_t size = EXT4_XATTR_LEN(name_len);
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		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_block && s->here->e_value_size) {
			void *first_val = s->base + min_offs;
			size_t offs = le16_to_cpu(s->here->e_value_offs);
			void *val = s->base + offs;
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			size_t size = EXT4_XATTR_SIZE(
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				le32_to_cpu(s->here->e_value_size));

570
			if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
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				/* The old and the new value have the same
				   size. Just replace. */
				s->here->e_value_size =
					cpu_to_le32(i->value_len);
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				memset(val + size - EXT4_XATTR_PAD, 0,
				       EXT4_XATTR_PAD); /* Clear pad bytes. */
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				memcpy(val, i->value, i->value_len);
				return 0;
			}

			/* 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_block &&
				    last->e_value_size && o < offs)
					last->e_value_offs =
						cpu_to_le16(o + size);
596
				last = EXT4_XATTR_NEXT(last);
597 598 599 600
			}
		}
		if (!i->value) {
			/* Remove the old name. */
601
			size_t size = EXT4_XATTR_LEN(name_len);
602 603 604 605 606 607 608 609 610 611 612
			last = ENTRY((void *)last - size);
			memmove(s->here, (void *)s->here + size,
				(void *)last - (void *)s->here + sizeof(__u32));
			memset(last, 0, size);
		}
	}

	if (i->value) {
		/* Insert the new value. */
		s->here->e_value_size = cpu_to_le32(i->value_len);
		if (i->value_len) {
613
			size_t size = EXT4_XATTR_SIZE(i->value_len);
614 615
			void *val = s->base + min_offs - size;
			s->here->e_value_offs = cpu_to_le16(min_offs - size);
616 617
			memset(val + size - EXT4_XATTR_PAD, 0,
			       EXT4_XATTR_PAD); /* Clear the pad bytes. */
618 619 620 621 622 623
			memcpy(val, i->value, i->value_len);
		}
	}
	return 0;
}

624 625
struct ext4_xattr_block_find {
	struct ext4_xattr_search s;
626 627 628 629
	struct buffer_head *bh;
};

static int
630 631
ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
		      struct ext4_xattr_block_find *bs)
632 633 634 635 636 637 638
{
	struct super_block *sb = inode->i_sb;
	int error;

	ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
		  i->name_index, i->name, i->value, (long)i->value_len);

639
	if (EXT4_I(inode)->i_file_acl) {
640
		/* The inode already has an extended attribute block. */
641
		bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
642 643 644 645 646 647
		error = -EIO;
		if (!bs->bh)
			goto cleanup;
		ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
			atomic_read(&(bs->bh->b_count)),
			le32_to_cpu(BHDR(bs->bh)->h_refcount));
648 649
		if (ext4_xattr_check_block(bs->bh)) {
			ext4_error(sb, __FUNCTION__,
650
				"inode %lu: bad block "E3FSBLK, inode->i_ino,
651
				EXT4_I(inode)->i_file_acl);
652 653 654 655 656 657 658 659
			error = -EIO;
			goto cleanup;
		}
		/* Find the named attribute. */
		bs->s.base = BHDR(bs->bh);
		bs->s.first = BFIRST(bs->bh);
		bs->s.end = bs->bh->b_data + bs->bh->b_size;
		bs->s.here = bs->s.first;
660
		error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
661 662 663 664 665 666 667 668 669 670 671 672
					      i->name, bs->bh->b_size, 1);
		if (error && error != -ENODATA)
			goto cleanup;
		bs->s.not_found = error;
	}
	error = 0;

cleanup:
	return error;
}

static int
673 674 675
ext4_xattr_block_set(handle_t *handle, struct inode *inode,
		     struct ext4_xattr_info *i,
		     struct ext4_xattr_block_find *bs)
676 677 678
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *new_bh = NULL;
679
	struct ext4_xattr_search *s = &bs->s;
680 681 682
	struct mb_cache_entry *ce = NULL;
	int error;

683
#define header(x) ((struct ext4_xattr_header *)(x))
684 685 686 687

	if (i->value && i->value_len > sb->s_blocksize)
		return -ENOSPC;
	if (s->base) {
688
		ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
689 690 691 692 693 694 695
					bs->bh->b_blocknr);
		if (header(s->base)->h_refcount == cpu_to_le32(1)) {
			if (ce) {
				mb_cache_entry_free(ce);
				ce = NULL;
			}
			ea_bdebug(bs->bh, "modifying in-place");
696
			error = ext4_journal_get_write_access(handle, bs->bh);
697 698 699
			if (error)
				goto cleanup;
			lock_buffer(bs->bh);
700
			error = ext4_xattr_set_entry(i, s);
701 702
			if (!error) {
				if (!IS_LAST_ENTRY(s->first))
703
					ext4_xattr_rehash(header(s->base),
704
							  s->here);
705
				ext4_xattr_cache_insert(bs->bh);
706 707 708 709 710
			}
			unlock_buffer(bs->bh);
			if (error == -EIO)
				goto bad_block;
			if (!error)
711
				error = ext4_journal_dirty_metadata(handle,
712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
								    bs->bh);
			if (error)
				goto cleanup;
			goto inserted;
		} else {
			int offset = (char *)s->here - bs->bh->b_data;

			if (ce) {
				mb_cache_entry_release(ce);
				ce = NULL;
			}
			ea_bdebug(bs->bh, "cloning");
			s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
			error = -ENOMEM;
			if (s->base == NULL)
				goto cleanup;
			memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
			s->first = ENTRY(header(s->base)+1);
			header(s->base)->h_refcount = cpu_to_le32(1);
			s->here = ENTRY(s->base + offset);
			s->end = s->base + bs->bh->b_size;
		}
	} else {
		/* Allocate a buffer where we construct the new block. */
		s->base = kmalloc(sb->s_blocksize, GFP_KERNEL);
		/* assert(header == s->base) */
		error = -ENOMEM;
		if (s->base == NULL)
			goto cleanup;
		memset(s->base, 0, sb->s_blocksize);
742
		header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
743 744 745 746 747 748 749
		header(s->base)->h_blocks = cpu_to_le32(1);
		header(s->base)->h_refcount = cpu_to_le32(1);
		s->first = ENTRY(header(s->base)+1);
		s->here = ENTRY(header(s->base)+1);
		s->end = s->base + sb->s_blocksize;
	}

750
	error = ext4_xattr_set_entry(i, s);
751 752 753 754 755
	if (error == -EIO)
		goto bad_block;
	if (error)
		goto cleanup;
	if (!IS_LAST_ENTRY(s->first))
756
		ext4_xattr_rehash(header(s->base), s->here);
757 758 759

inserted:
	if (!IS_LAST_ENTRY(s->first)) {
760
		new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
761 762 763 764 765 766 767 768 769 770
		if (new_bh) {
			/* We found an identical block in the cache. */
			if (new_bh == bs->bh)
				ea_bdebug(new_bh, "keeping");
			else {
				/* The old block is released after updating
				   the inode. */
				error = -EDQUOT;
				if (DQUOT_ALLOC_BLOCK(inode, 1))
					goto cleanup;
771
				error = ext4_journal_get_write_access(handle,
772 773 774 775 776 777 778 779 780
								      new_bh);
				if (error)
					goto cleanup_dquot;
				lock_buffer(new_bh);
				BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
					le32_to_cpu(BHDR(new_bh)->h_refcount));
				ea_bdebug(new_bh, "reusing; refcount now=%d",
					le32_to_cpu(BHDR(new_bh)->h_refcount));
				unlock_buffer(new_bh);
781
				error = ext4_journal_dirty_metadata(handle,
782 783 784 785 786 787 788 789 790 791 792 793 794
								    new_bh);
				if (error)
					goto cleanup_dquot;
			}
			mb_cache_entry_release(ce);
			ce = NULL;
		} else if (bs->bh && s->base == bs->bh->b_data) {
			/* We were modifying this block in-place. */
			ea_bdebug(bs->bh, "keeping this block");
			new_bh = bs->bh;
			get_bh(new_bh);
		} else {
			/* We need to allocate a new block */
795 796 797 798 799
			ext4_fsblk_t goal = le32_to_cpu(
					EXT4_SB(sb)->s_es->s_first_data_block) +
				(ext4_fsblk_t)EXT4_I(inode)->i_block_group *
				EXT4_BLOCKS_PER_GROUP(sb);
			ext4_fsblk_t block = ext4_new_block(handle, inode,
800 801 802 803 804 805 806 807
							goal, &error);
			if (error)
				goto cleanup;
			ea_idebug(inode, "creating block %d", block);

			new_bh = sb_getblk(sb, block);
			if (!new_bh) {
getblk_failed:
808
				ext4_free_blocks(handle, inode, block, 1);
809 810 811 812
				error = -EIO;
				goto cleanup;
			}
			lock_buffer(new_bh);
813
			error = ext4_journal_get_create_access(handle, new_bh);
814 815 816 817 818 819 820
			if (error) {
				unlock_buffer(new_bh);
				goto getblk_failed;
			}
			memcpy(new_bh->b_data, s->base, new_bh->b_size);
			set_buffer_uptodate(new_bh);
			unlock_buffer(new_bh);
821 822
			ext4_xattr_cache_insert(new_bh);
			error = ext4_journal_dirty_metadata(handle, new_bh);
823 824 825 826 827 828
			if (error)
				goto cleanup;
		}
	}

	/* Update the inode. */
829
	EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
830 831 832

	/* Drop the previous xattr block. */
	if (bs->bh && bs->bh != new_bh)
833
		ext4_xattr_release_block(handle, inode, bs->bh);
834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849
	error = 0;

cleanup:
	if (ce)
		mb_cache_entry_release(ce);
	brelse(new_bh);
	if (!(bs->bh && s->base == bs->bh->b_data))
		kfree(s->base);

	return error;

cleanup_dquot:
	DQUOT_FREE_BLOCK(inode, 1);
	goto cleanup;

bad_block:
850
	ext4_error(inode->i_sb, __FUNCTION__,
851
		   "inode %lu: bad block "E3FSBLK, inode->i_ino,
852
		   EXT4_I(inode)->i_file_acl);
853 854 855 856 857
	goto cleanup;

#undef header
}

858 859 860
struct ext4_xattr_ibody_find {
	struct ext4_xattr_search s;
	struct ext4_iloc iloc;
861 862 863
};

static int
864 865
ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
		      struct ext4_xattr_ibody_find *is)
866
{
867 868
	struct ext4_xattr_ibody_header *header;
	struct ext4_inode *raw_inode;
869 870
	int error;

871
	if (EXT4_I(inode)->i_extra_isize == 0)
872
		return 0;
873
	raw_inode = ext4_raw_inode(&is->iloc);
874 875 876
	header = IHDR(inode, raw_inode);
	is->s.base = is->s.first = IFIRST(header);
	is->s.here = is->s.first;
877 878 879
	is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
	if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
		error = ext4_xattr_check_names(IFIRST(header), is->s.end);
880 881 882
		if (error)
			return error;
		/* Find the named attribute. */
883
		error = ext4_xattr_find_entry(&is->s.here, i->name_index,
884 885 886 887 888 889 890 891 892 893
					      i->name, is->s.end -
					      (void *)is->s.base, 0);
		if (error && error != -ENODATA)
			return error;
		is->s.not_found = error;
	}
	return 0;
}

static int
894 895 896
ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
		     struct ext4_xattr_info *i,
		     struct ext4_xattr_ibody_find *is)
897
{
898 899
	struct ext4_xattr_ibody_header *header;
	struct ext4_xattr_search *s = &is->s;
900 901
	int error;

902
	if (EXT4_I(inode)->i_extra_isize == 0)
903
		return -ENOSPC;
904
	error = ext4_xattr_set_entry(i, s);
905 906
	if (error)
		return error;
907
	header = IHDR(inode, ext4_raw_inode(&is->iloc));
908
	if (!IS_LAST_ENTRY(s->first)) {
909 910
		header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
		EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
911 912
	} else {
		header->h_magic = cpu_to_le32(0);
913
		EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
914 915 916 917 918
	}
	return 0;
}

/*
919
 * ext4_xattr_set_handle()
920 921 922 923 924 925 926 927 928 929 930
 *
 * Create, replace or remove an extended attribute for this inode. Buffer
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int
931
ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
932 933 934
		      const char *name, const void *value, size_t value_len,
		      int flags)
{
935
	struct ext4_xattr_info i = {
936 937 938 939 940 941
		.name_index = name_index,
		.name = name,
		.value = value,
		.value_len = value_len,

	};
942
	struct ext4_xattr_ibody_find is = {
943 944
		.s = { .not_found = -ENODATA, },
	};
945
	struct ext4_xattr_block_find bs = {
946 947 948 949 950 951 952 953
		.s = { .not_found = -ENODATA, },
	};
	int error;

	if (!name)
		return -EINVAL;
	if (strlen(name) > 255)
		return -ERANGE;
954 955
	down_write(&EXT4_I(inode)->xattr_sem);
	error = ext4_get_inode_loc(inode, &is.iloc);
956 957 958
	if (error)
		goto cleanup;

959 960 961 962
	if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
		struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
		EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
963 964
	}

965
	error = ext4_xattr_ibody_find(inode, &i, &is);
966 967 968
	if (error)
		goto cleanup;
	if (is.s.not_found)
969
		error = ext4_xattr_block_find(inode, &i, &bs);
970 971 972 973 974 975 976 977 978 979 980 981 982 983
	if (error)
		goto cleanup;
	if (is.s.not_found && bs.s.not_found) {
		error = -ENODATA;
		if (flags & XATTR_REPLACE)
			goto cleanup;
		error = 0;
		if (!value)
			goto cleanup;
	} else {
		error = -EEXIST;
		if (flags & XATTR_CREATE)
			goto cleanup;
	}
984
	error = ext4_journal_get_write_access(handle, is.iloc.bh);
985 986 987 988
	if (error)
		goto cleanup;
	if (!value) {
		if (!is.s.not_found)
989
			error = ext4_xattr_ibody_set(handle, inode, &i, &is);
990
		else if (!bs.s.not_found)
991
			error = ext4_xattr_block_set(handle, inode, &i, &bs);
992
	} else {
993
		error = ext4_xattr_ibody_set(handle, inode, &i, &is);
994 995
		if (!error && !bs.s.not_found) {
			i.value = NULL;
996
			error = ext4_xattr_block_set(handle, inode, &i, &bs);
997
		} else if (error == -ENOSPC) {
998
			error = ext4_xattr_block_set(handle, inode, &i, &bs);
999 1000 1001 1002
			if (error)
				goto cleanup;
			if (!is.s.not_found) {
				i.value = NULL;
1003
				error = ext4_xattr_ibody_set(handle, inode, &i,
1004 1005 1006 1007 1008
							     &is);
			}
		}
	}
	if (!error) {
1009
		ext4_xattr_update_super_block(handle, inode->i_sb);
1010
		inode->i_ctime = CURRENT_TIME_SEC;
1011
		error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1012
		/*
1013
		 * The bh is consumed by ext4_mark_iloc_dirty, even with
1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
		 * error != 0.
		 */
		is.iloc.bh = NULL;
		if (IS_SYNC(inode))
			handle->h_sync = 1;
	}

cleanup:
	brelse(is.iloc.bh);
	brelse(bs.bh);
1024
	up_write(&EXT4_I(inode)->xattr_sem);
1025 1026 1027 1028
	return error;
}

/*
1029
 * ext4_xattr_set()
1030
 *
1031
 * Like ext4_xattr_set_handle, but start from an inode. This extended
1032 1033 1034 1035 1036
 * attribute modification is a filesystem transaction by itself.
 *
 * Returns 0, or a negative error number on failure.
 */
int
1037
ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1038 1039 1040 1041 1042 1043
	       const void *value, size_t value_len, int flags)
{
	handle_t *handle;
	int error, retries = 0;

retry:
1044
	handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1045 1046 1047 1048 1049
	if (IS_ERR(handle)) {
		error = PTR_ERR(handle);
	} else {
		int error2;

1050
		error = ext4_xattr_set_handle(handle, inode, name_index, name,
1051
					      value, value_len, flags);
1052
		error2 = ext4_journal_stop(handle);
1053
		if (error == -ENOSPC &&
1054
		    ext4_should_retry_alloc(inode->i_sb, &retries))
1055 1056 1057 1058 1059 1060 1061 1062 1063
			goto retry;
		if (error == 0)
			error = error2;
	}

	return error;
}

/*
1064
 * ext4_xattr_delete_inode()
1065 1066 1067 1068 1069 1070
 *
 * Free extended attribute resources associated with this inode. This
 * is called immediately before an inode is freed. We have exclusive
 * access to the inode.
 */
void
1071
ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1072 1073 1074
{
	struct buffer_head *bh = NULL;

1075
	if (!EXT4_I(inode)->i_file_acl)
1076
		goto cleanup;
1077
	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1078
	if (!bh) {
1079
		ext4_error(inode->i_sb, __FUNCTION__,
1080
			"inode %lu: block "E3FSBLK" read error", inode->i_ino,
1081
			EXT4_I(inode)->i_file_acl);
1082 1083
		goto cleanup;
	}
1084
	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1085
	    BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1086
		ext4_error(inode->i_sb, __FUNCTION__,
1087
			"inode %lu: bad block "E3FSBLK, inode->i_ino,
1088
			EXT4_I(inode)->i_file_acl);
1089 1090
		goto cleanup;
	}
1091 1092
	ext4_xattr_release_block(handle, inode, bh);
	EXT4_I(inode)->i_file_acl = 0;
1093 1094 1095 1096 1097 1098

cleanup:
	brelse(bh);
}

/*
1099
 * ext4_xattr_put_super()
1100 1101 1102 1103
 *
 * This is called when a file system is unmounted.
 */
void
1104
ext4_xattr_put_super(struct super_block *sb)
1105 1106 1107 1108 1109
{
	mb_cache_shrink(sb->s_bdev);
}

/*
1110
 * ext4_xattr_cache_insert()
1111 1112 1113 1114 1115 1116 1117
 *
 * Create a new entry in the extended attribute cache, and insert
 * it unless such an entry is already in the cache.
 *
 * Returns 0, or a negative error number on failure.
 */
static void
1118
ext4_xattr_cache_insert(struct buffer_head *bh)
1119 1120 1121 1122 1123
{
	__u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
	struct mb_cache_entry *ce;
	int error;

1124
	ce = mb_cache_entry_alloc(ext4_xattr_cache);
1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142
	if (!ce) {
		ea_bdebug(bh, "out of memory");
		return;
	}
	error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
	if (error) {
		mb_cache_entry_free(ce);
		if (error == -EBUSY) {
			ea_bdebug(bh, "already in cache");
			error = 0;
		}
	} else {
		ea_bdebug(bh, "inserting [%x]", (int)hash);
		mb_cache_entry_release(ce);
	}
}

/*
1143
 * ext4_xattr_cmp()
1144 1145 1146 1147 1148 1149 1150
 *
 * Compare two extended attribute blocks for equality.
 *
 * Returns 0 if the blocks are equal, 1 if they differ, and
 * a negative error number on errors.
 */
static int
1151 1152
ext4_xattr_cmp(struct ext4_xattr_header *header1,
	       struct ext4_xattr_header *header2)
1153
{
1154
	struct ext4_xattr_entry *entry1, *entry2;
1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173

	entry1 = ENTRY(header1+1);
	entry2 = ENTRY(header2+1);
	while (!IS_LAST_ENTRY(entry1)) {
		if (IS_LAST_ENTRY(entry2))
			return 1;
		if (entry1->e_hash != entry2->e_hash ||
		    entry1->e_name_index != entry2->e_name_index ||
		    entry1->e_name_len != entry2->e_name_len ||
		    entry1->e_value_size != entry2->e_value_size ||
		    memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
			return 1;
		if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
			return -EIO;
		if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
			   (char *)header2 + le16_to_cpu(entry2->e_value_offs),
			   le32_to_cpu(entry1->e_value_size)))
			return 1;

1174 1175
		entry1 = EXT4_XATTR_NEXT(entry1);
		entry2 = EXT4_XATTR_NEXT(entry2);
1176 1177 1178 1179 1180 1181 1182
	}
	if (!IS_LAST_ENTRY(entry2))
		return 1;
	return 0;
}

/*
1183
 * ext4_xattr_cache_find()
1184 1185 1186 1187 1188 1189 1190
 *
 * Find an identical extended attribute block.
 *
 * Returns a pointer to the block found, or NULL if such a block was
 * not found or an error occurred.
 */
static struct buffer_head *
1191
ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1192 1193 1194 1195 1196 1197 1198 1199 1200
		      struct mb_cache_entry **pce)
{
	__u32 hash = le32_to_cpu(header->h_hash);
	struct mb_cache_entry *ce;

	if (!header->h_hash)
		return NULL;  /* never share */
	ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
again:
1201
	ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212
				       inode->i_sb->s_bdev, 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) {
1213
			ext4_error(inode->i_sb, __FUNCTION__,
1214 1215 1216
				"inode %lu: block %lu read error",
				inode->i_ino, (unsigned long) ce->e_block);
		} else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1217
				EXT4_XATTR_REFCOUNT_MAX) {
1218 1219 1220
			ea_idebug(inode, "block %lu refcount %d>=%d",
				  (unsigned long) ce->e_block,
				  le32_to_cpu(BHDR(bh)->h_refcount),
1221 1222
					  EXT4_XATTR_REFCOUNT_MAX);
		} else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235
			*pce = ce;
			return bh;
		}
		brelse(bh);
		ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
	}
	return NULL;
}

#define NAME_HASH_SHIFT 5
#define VALUE_HASH_SHIFT 16

/*
1236
 * ext4_xattr_hash_entry()
1237 1238 1239
 *
 * Compute the hash of an extended attribute.
 */
1240 1241
static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
					 struct ext4_xattr_entry *entry)
1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256
{
	__u32 hash = 0;
	char *name = entry->e_name;
	int n;

	for (n=0; n < entry->e_name_len; n++) {
		hash = (hash << NAME_HASH_SHIFT) ^
		       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
		       *name++;
	}

	if (entry->e_value_block == 0 && entry->e_value_size != 0) {
		__le32 *value = (__le32 *)((char *)header +
			le16_to_cpu(entry->e_value_offs));
		for (n = (le32_to_cpu(entry->e_value_size) +
1257
		     EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271
			hash = (hash << VALUE_HASH_SHIFT) ^
			       (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
			       le32_to_cpu(*value++);
		}
	}
	entry->e_hash = cpu_to_le32(hash);
}

#undef NAME_HASH_SHIFT
#undef VALUE_HASH_SHIFT

#define BLOCK_HASH_SHIFT 16

/*
1272
 * ext4_xattr_rehash()
1273 1274 1275
 *
 * Re-compute the extended attribute hash value after an entry has changed.
 */
1276 1277
static void ext4_xattr_rehash(struct ext4_xattr_header *header,
			      struct ext4_xattr_entry *entry)
1278
{
1279
	struct ext4_xattr_entry *here;
1280 1281
	__u32 hash = 0;

1282
	ext4_xattr_hash_entry(header, entry);
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292
	here = ENTRY(header+1);
	while (!IS_LAST_ENTRY(here)) {
		if (!here->e_hash) {
			/* Block is not shared if an entry's hash value == 0 */
			hash = 0;
			break;
		}
		hash = (hash << BLOCK_HASH_SHIFT) ^
		       (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
		       le32_to_cpu(here->e_hash);
1293
		here = EXT4_XATTR_NEXT(here);
1294 1295 1296 1297 1298 1299 1300
	}
	header->h_hash = cpu_to_le32(hash);
}

#undef BLOCK_HASH_SHIFT

int __init
1301
init_ext4_xattr(void)
1302
{
1303
	ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1304 1305
		sizeof(struct mb_cache_entry) +
		sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1306
	if (!ext4_xattr_cache)
1307 1308 1309 1310 1311
		return -ENOMEM;
	return 0;
}

void
1312
exit_ext4_xattr(void)
1313
{
1314 1315 1316
	if (ext4_xattr_cache)
		mb_cache_destroy(ext4_xattr_cache);
	ext4_xattr_cache = NULL;
1317
}