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linux/fs/ext2/xattr.c
Andreas Gruenbacher 2aec7c5232 mbcache: Remove unused features 
The mbcache code was written to support a variable number of indexes,
but all the existing users use exactly one index.  Simplify to code to
support only that case.

There are also no users of the cache entry free operation, and none of
the users keep extra data in cache entries.  Remove those features as
well.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-09 16:48:45 -04:00

1040 lines
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/*
* linux/fs/ext2/xattr.c
*
* Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
*
* Fix by Harrison Xing <harrison@mountainviewdata.com>.
* 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.
*
*/
/*
* Extended attributes are stored on disk blocks allocated outside of
* any inode. The i_file_acl field is then made to point to this allocated
* block. If all extended attributes of an inode are identical, these
* inodes may share the same extended attribute block. Such situations
* are automatically detected by keeping a cache of recent attribute block
* numbers and hashes over the block's contents in memory.
*
*
* Extended attribute block layout:
*
* +------------------+
* | header |
* | entry 1 | |
* | entry 2 | | growing downwards
* | entry 3 | v
* | four null bytes |
* | . . . |
* | value 1 | ^
* | value 3 | | growing upwards
* | value 2 | |
* +------------------+
*
* The block header is followed by multiple entry descriptors. These entry
* descriptors are variable in size, and alligned to EXT2_XATTR_PAD
* byte boundaries. The entry descriptors are sorted by attribute name,
* so that two extended attribute blocks can be compared efficiently.
*
* Attribute values are aligned to the end of the block, stored in
* no specific order. They are also padded to EXT2_XATTR_PAD byte
* boundaries. No additional gaps are left between them.
*
* Locking strategy
* ----------------
* EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
* 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 will change. Multiple writers to an EA block are synchronized
* by the bh lock. No more than a single bh lock is held at any time
* to avoid deadlocks.
*/
#include <linux/buffer_head.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mbcache.h>
#include <linux/quotaops.h>
#include <linux/rwsem.h>
#include <linux/security.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
#ifdef EXT2_XATTR_DEBUG
# define ea_idebug(inode, f...) do { \
printk(KERN_DEBUG "inode %s:%ld: ", \
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
static int ext2_xattr_set2(struct inode *, struct buffer_head *,
struct ext2_xattr_header *);
static int ext2_xattr_cache_insert(struct buffer_head *);
static struct buffer_head *ext2_xattr_cache_find(struct inode *,
struct ext2_xattr_header *);
static void ext2_xattr_rehash(struct ext2_xattr_header *,
struct ext2_xattr_entry *);
static struct mb_cache *ext2_xattr_cache;
static const struct xattr_handler *ext2_xattr_handler_map[] = {
[EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
#ifdef CONFIG_EXT2_FS_POSIX_ACL
[EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
[EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
#endif
[EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
#ifdef CONFIG_EXT2_FS_SECURITY
[EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
#endif
};
const struct xattr_handler *ext2_xattr_handlers[] = {
&ext2_xattr_user_handler,
&ext2_xattr_trusted_handler,
#ifdef CONFIG_EXT2_FS_POSIX_ACL
&ext2_xattr_acl_access_handler,
&ext2_xattr_acl_default_handler,
#endif
#ifdef CONFIG_EXT2_FS_SECURITY
&ext2_xattr_security_handler,
#endif
NULL
};
static inline const struct xattr_handler *
ext2_xattr_handler(int name_index)
{
const struct xattr_handler *handler = NULL;
if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
handler = ext2_xattr_handler_map[name_index];
return handler;
}
/*
* ext2_xattr_get()
*
* 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
ext2_xattr_get(struct inode *inode, int name_index, const char *name,
void *buffer, size_t buffer_size)
{
struct buffer_head *bh = NULL;
struct ext2_xattr_entry *entry;
size_t name_len, size;
char *end;
int error;
ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
name_index, name, buffer, (long)buffer_size);
if (name == NULL)
return -EINVAL;
down_read(&EXT2_I(inode)->xattr_sem);
error = -ENODATA;
if (!EXT2_I(inode)->i_file_acl)
goto cleanup;
ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
error = -EIO;
if (!bh)
goto cleanup;
ea_bdebug(bh, "b_count=%d, refcount=%d",
atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
end = bh->b_data + bh->b_size;
if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
HDR(bh)->h_blocks != cpu_to_le32(1)) {
bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
"inode %ld: bad block %d", inode->i_ino,
EXT2_I(inode)->i_file_acl);
error = -EIO;
goto cleanup;
}
/* find named attribute */
name_len = strlen(name);
error = -ERANGE;
if (name_len > 255)
goto cleanup;
entry = FIRST_ENTRY(bh);
while (!IS_LAST_ENTRY(entry)) {
struct ext2_xattr_entry *next =
EXT2_XATTR_NEXT(entry);
if ((char *)next >= end)
goto bad_block;
if (name_index == entry->e_name_index &&
name_len == entry->e_name_len &&
memcmp(name, entry->e_name, name_len) == 0)
goto found;
entry = next;
}
/* Check the remaining name entries */
while (!IS_LAST_ENTRY(entry)) {
struct ext2_xattr_entry *next =
EXT2_XATTR_NEXT(entry);
if ((char *)next >= end)
goto bad_block;
entry = next;
}
if (ext2_xattr_cache_insert(bh))
ea_idebug(inode, "cache insert failed");
error = -ENODATA;
goto cleanup;
found:
/* check the buffer size */
if (entry->e_value_block != 0)
goto bad_block;
size = le32_to_cpu(entry->e_value_size);
if (size > inode->i_sb->s_blocksize ||
le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
goto bad_block;
if (ext2_xattr_cache_insert(bh))
ea_idebug(inode, "cache insert failed");
if (buffer) {
error = -ERANGE;
if (size > buffer_size)
goto cleanup;
/* return value of attribute */
memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
size);
}
error = size;
cleanup:
brelse(bh);
up_read(&EXT2_I(inode)->xattr_sem);
return error;
}
/*
* ext2_xattr_list()
*
* 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.
*/
static int
ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{
struct inode *inode = dentry->d_inode;
struct buffer_head *bh = NULL;
struct ext2_xattr_entry *entry;
char *end;
size_t rest = buffer_size;
int error;
ea_idebug(inode, "buffer=%p, buffer_size=%ld",
buffer, (long)buffer_size);
down_read(&EXT2_I(inode)->xattr_sem);
error = 0;
if (!EXT2_I(inode)->i_file_acl)
goto cleanup;
ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
error = -EIO;
if (!bh)
goto cleanup;
ea_bdebug(bh, "b_count=%d, refcount=%d",
atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
end = bh->b_data + bh->b_size;
if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
HDR(bh)->h_blocks != cpu_to_le32(1)) {
bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
"inode %ld: bad block %d", inode->i_ino,
EXT2_I(inode)->i_file_acl);
error = -EIO;
goto cleanup;
}
/* check the on-disk data structure */
entry = FIRST_ENTRY(bh);
while (!IS_LAST_ENTRY(entry)) {
struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
if ((char *)next >= end)
goto bad_block;
entry = next;
}
if (ext2_xattr_cache_insert(bh))
ea_idebug(inode, "cache insert failed");
/* list the attribute names */
for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
entry = EXT2_XATTR_NEXT(entry)) {
const struct xattr_handler *handler =
ext2_xattr_handler(entry->e_name_index);
if (handler) {
size_t size = handler->list(dentry, buffer, rest,
entry->e_name,
entry->e_name_len,
handler->flags);
if (buffer) {
if (size > rest) {
error = -ERANGE;
goto cleanup;
}
buffer += size;
}
rest -= size;
}
}
error = buffer_size - rest; /* total size */
cleanup:
brelse(bh);
up_read(&EXT2_I(inode)->xattr_sem);
return error;
}
/*
* Inode operation listxattr()
*
* dentry->d_inode->i_mutex: don't care
*/
ssize_t
ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
return ext2_xattr_list(dentry, buffer, size);
}
/*
* If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
* not set, set it.
*/
static void ext2_xattr_update_super_block(struct super_block *sb)
{
if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
return;
spin_lock(&EXT2_SB(sb)->s_lock);
EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
spin_unlock(&EXT2_SB(sb)->s_lock);
sb->s_dirt = 1;
mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
}
/*
* ext2_xattr_set()
*
* 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
ext2_xattr_set(struct inode *inode, int name_index, const char *name,
const void *value, size_t value_len, int flags)
{
struct super_block *sb = inode->i_sb;
struct buffer_head *bh = NULL;
struct ext2_xattr_header *header = NULL;
struct ext2_xattr_entry *here, *last;
size_t name_len, free, min_offs = sb->s_blocksize;
int not_found = 1, error;
char *end;
/*
* header -- Points either into bh, or to a temporarily
* allocated buffer.
* here -- The named entry found, or the place for inserting, within
* the block pointed to by header.
* last -- Points right after the last named entry within the block
* pointed to by header.
* min_offs -- The offset of the first value (values are aligned
* towards the end of the block).
* end -- Points right after the block pointed to by header.
*/
ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
name_index, name, value, (long)value_len);
if (value == NULL)
value_len = 0;
if (name == NULL)
return -EINVAL;
name_len = strlen(name);
if (name_len > 255 || value_len > sb->s_blocksize)
return -ERANGE;
down_write(&EXT2_I(inode)->xattr_sem);
if (EXT2_I(inode)->i_file_acl) {
/* The inode already has an extended attribute block. */
bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
error = -EIO;
if (!bh)
goto cleanup;
ea_bdebug(bh, "b_count=%d, refcount=%d",
atomic_read(&(bh->b_count)),
le32_to_cpu(HDR(bh)->h_refcount));
header = HDR(bh);
end = bh->b_data + bh->b_size;
if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
header->h_blocks != cpu_to_le32(1)) {
bad_block: ext2_error(sb, "ext2_xattr_set",
"inode %ld: bad block %d", inode->i_ino,
EXT2_I(inode)->i_file_acl);
error = -EIO;
goto cleanup;
}
/* Find the named attribute. */
here = FIRST_ENTRY(bh);
while (!IS_LAST_ENTRY(here)) {
struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
if ((char *)next >= end)
goto bad_block;
if (!here->e_value_block && here->e_value_size) {
size_t offs = le16_to_cpu(here->e_value_offs);
if (offs < min_offs)
min_offs = offs;
}
not_found = name_index - here->e_name_index;
if (!not_found)
not_found = name_len - here->e_name_len;
if (!not_found)
not_found = memcmp(name, here->e_name,name_len);
if (not_found <= 0)
break;
here = next;
}
last = here;
/* We still need to compute min_offs and last. */
while (!IS_LAST_ENTRY(last)) {
struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
if ((char *)next >= end)
goto bad_block;
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;
}
last = next;
}
/* Check whether we have enough space left. */
free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
} else {
/* We will use a new extended attribute block. */
free = sb->s_blocksize -
sizeof(struct ext2_xattr_header) - sizeof(__u32);
here = last = NULL; /* avoid gcc uninitialized warning. */
}
if (not_found) {
/* Request to remove a nonexistent attribute? */
error = -ENODATA;
if (flags & XATTR_REPLACE)
goto cleanup;
error = 0;
if (value == NULL)
goto cleanup;
} else {
/* Request to create an existing attribute? */
error = -EEXIST;
if (flags & XATTR_CREATE)
goto cleanup;
if (!here->e_value_block && here->e_value_size) {
size_t size = le32_to_cpu(here->e_value_size);
if (le16_to_cpu(here->e_value_offs) + size >
sb->s_blocksize || size > sb->s_blocksize)
goto bad_block;
free += EXT2_XATTR_SIZE(size);
}
free += EXT2_XATTR_LEN(name_len);
}
error = -ENOSPC;
if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
goto cleanup;
/* Here we know that we can set the new attribute. */
if (header) {
struct mb_cache_entry *ce;
/* assert(header == HDR(bh)); */
ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
bh->b_blocknr);
lock_buffer(bh);
if (header->h_refcount == cpu_to_le32(1)) {
ea_bdebug(bh, "modifying in-place");
if (ce)
mb_cache_entry_free(ce);
/* keep the buffer locked while modifying it. */
} else {
int offset;
if (ce)
mb_cache_entry_release(ce);
unlock_buffer(bh);
ea_bdebug(bh, "cloning");
header = kmalloc(bh->b_size, GFP_KERNEL);
error = -ENOMEM;
if (header == NULL)
goto cleanup;
memcpy(header, HDR(bh), bh->b_size);
header->h_refcount = cpu_to_le32(1);
offset = (char *)here - bh->b_data;
here = ENTRY((char *)header + offset);
offset = (char *)last - bh->b_data;
last = ENTRY((char *)header + offset);
}
} else {
/* Allocate a buffer where we construct the new block. */
header = kzalloc(sb->s_blocksize, GFP_KERNEL);
error = -ENOMEM;
if (header == NULL)
goto cleanup;
end = (char *)header + sb->s_blocksize;
header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
header->h_blocks = header->h_refcount = cpu_to_le32(1);
last = here = ENTRY(header+1);
}
/* Iff we are modifying the block in-place, bh is locked here. */
if (not_found) {
/* Insert the new name. */
size_t size = EXT2_XATTR_LEN(name_len);
size_t rest = (char *)last - (char *)here;
memmove((char *)here + size, here, rest);
memset(here, 0, size);
here->e_name_index = name_index;
here->e_name_len = name_len;
memcpy(here->e_name, name, name_len);
} else {
if (!here->e_value_block && here->e_value_size) {
char *first_val = (char *)header + min_offs;
size_t offs = le16_to_cpu(here->e_value_offs);
char *val = (char *)header + offs;
size_t size = EXT2_XATTR_SIZE(
le32_to_cpu(here->e_value_size));
if (size == EXT2_XATTR_SIZE(value_len)) {
/* The old and the new value have the same
size. Just replace. */
here->e_value_size = cpu_to_le32(value_len);
memset(val + size - EXT2_XATTR_PAD, 0,
EXT2_XATTR_PAD); /* Clear pad bytes. */
memcpy(val, value, value_len);
goto skip_replace;
}
/* Remove the old value. */
memmove(first_val + size, first_val, val - first_val);
memset(first_val, 0, size);
here->e_value_offs = 0;
min_offs += size;
/* Adjust all value offsets. */
last = ENTRY(header+1);
while (!IS_LAST_ENTRY(last)) {
size_t o = le16_to_cpu(last->e_value_offs);
if (!last->e_value_block && o < offs)
last->e_value_offs =
cpu_to_le16(o + size);
last = EXT2_XATTR_NEXT(last);
}
}
if (value == NULL) {
/* Remove the old name. */
size_t size = EXT2_XATTR_LEN(name_len);
last = ENTRY((char *)last - size);
memmove(here, (char*)here + size,
(char*)last - (char*)here);
memset(last, 0, size);
}
}
if (value != NULL) {
/* Insert the new value. */
here->e_value_size = cpu_to_le32(value_len);
if (value_len) {
size_t size = EXT2_XATTR_SIZE(value_len);
char *val = (char *)header + min_offs - size;
here->e_value_offs =
cpu_to_le16((char *)val - (char *)header);
memset(val + size - EXT2_XATTR_PAD, 0,
EXT2_XATTR_PAD); /* Clear the pad bytes. */
memcpy(val, value, value_len);
}
}
skip_replace:
if (IS_LAST_ENTRY(ENTRY(header+1))) {
/* This block is now empty. */
if (bh && header == HDR(bh))
unlock_buffer(bh); /* we were modifying in-place. */
error = ext2_xattr_set2(inode, bh, NULL);
} else {
ext2_xattr_rehash(header, here);
if (bh && header == HDR(bh))
unlock_buffer(bh); /* we were modifying in-place. */
error = ext2_xattr_set2(inode, bh, header);
}
cleanup:
brelse(bh);
if (!(bh && header == HDR(bh)))
kfree(header);
up_write(&EXT2_I(inode)->xattr_sem);
return error;
}
/*
* Second half of ext2_xattr_set(): Update the file system.
*/
static int
ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
struct ext2_xattr_header *header)
{
struct super_block *sb = inode->i_sb;
struct buffer_head *new_bh = NULL;
int error;
if (header) {
new_bh = ext2_xattr_cache_find(inode, header);
if (new_bh) {
/* We found an identical block in the cache. */
if (new_bh == old_bh) {
ea_bdebug(new_bh, "keeping this block");
} else {
/* The old block is released after updating
the inode. */
ea_bdebug(new_bh, "reusing block");
error = dquot_alloc_block(inode, 1);
if (error) {
unlock_buffer(new_bh);
goto cleanup;
}
le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
ea_bdebug(new_bh, "refcount now=%d",
le32_to_cpu(HDR(new_bh)->h_refcount));
}
unlock_buffer(new_bh);
} else if (old_bh && header == HDR(old_bh)) {
/* Keep this block. No need to lock the block as we
don't need to change the reference count. */
new_bh = old_bh;
get_bh(new_bh);
ext2_xattr_cache_insert(new_bh);
} else {
/* We need to allocate a new block */
ext2_fsblk_t goal = ext2_group_first_block_no(sb,
EXT2_I(inode)->i_block_group);
int block = ext2_new_block(inode, goal, &error);
if (error)
goto cleanup;
ea_idebug(inode, "creating block %d", block);
new_bh = sb_getblk(sb, block);
if (!new_bh) {
ext2_free_blocks(inode, block, 1);
mark_inode_dirty(inode);
error = -EIO;
goto cleanup;
}
lock_buffer(new_bh);
memcpy(new_bh->b_data, header, new_bh->b_size);
set_buffer_uptodate(new_bh);
unlock_buffer(new_bh);
ext2_xattr_cache_insert(new_bh);
ext2_xattr_update_super_block(sb);
}
mark_buffer_dirty(new_bh);
if (IS_SYNC(inode)) {
sync_dirty_buffer(new_bh);
error = -EIO;
if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
goto cleanup;
}
}
/* Update the inode. */
EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
inode->i_ctime = CURRENT_TIME_SEC;
if (IS_SYNC(inode)) {
error = ext2_sync_inode (inode);
/* In case sync failed due to ENOSPC the inode was actually
* written (only some dirty data were not) so we just proceed
* as if nothing happened and cleanup the unused block */
if (error && error != -ENOSPC) {
if (new_bh && new_bh != old_bh) {
dquot_free_block_nodirty(inode, 1);
mark_inode_dirty(inode);
}
goto cleanup;
}
} else
mark_inode_dirty(inode);
error = 0;
if (old_bh && old_bh != new_bh) {
struct mb_cache_entry *ce;
/*
* If there was an old block and we are no longer using it,
* release the old block.
*/
ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
old_bh->b_blocknr);
lock_buffer(old_bh);
if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
/* Free the old block. */
if (ce)
mb_cache_entry_free(ce);
ea_bdebug(old_bh, "freeing");
ext2_free_blocks(inode, old_bh->b_blocknr, 1);
mark_inode_dirty(inode);
/* We let our caller release old_bh, so we
* need to duplicate the buffer before. */
get_bh(old_bh);
bforget(old_bh);
} else {
/* Decrement the refcount only. */
le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
if (ce)
mb_cache_entry_release(ce);
dquot_free_block_nodirty(inode, 1);
mark_inode_dirty(inode);
mark_buffer_dirty(old_bh);
ea_bdebug(old_bh, "refcount now=%d",
le32_to_cpu(HDR(old_bh)->h_refcount));
}
unlock_buffer(old_bh);
}
cleanup:
brelse(new_bh);
return error;
}
/*
* ext2_xattr_delete_inode()
*
* Free extended attribute resources associated with this inode. This
* is called immediately before an inode is freed.
*/
void
ext2_xattr_delete_inode(struct inode *inode)
{
struct buffer_head *bh = NULL;
struct mb_cache_entry *ce;
down_write(&EXT2_I(inode)->xattr_sem);
if (!EXT2_I(inode)->i_file_acl)
goto cleanup;
bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
if (!bh) {
ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
"inode %ld: block %d read error", inode->i_ino,
EXT2_I(inode)->i_file_acl);
goto cleanup;
}
ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
HDR(bh)->h_blocks != cpu_to_le32(1)) {
ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
"inode %ld: bad block %d", inode->i_ino,
EXT2_I(inode)->i_file_acl);
goto cleanup;
}
ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
lock_buffer(bh);
if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
if (ce)
mb_cache_entry_free(ce);
ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
get_bh(bh);
bforget(bh);
unlock_buffer(bh);
} else {
le32_add_cpu(&HDR(bh)->h_refcount, -1);
if (ce)
mb_cache_entry_release(ce);
ea_bdebug(bh, "refcount now=%d",
le32_to_cpu(HDR(bh)->h_refcount));
unlock_buffer(bh);
mark_buffer_dirty(bh);
if (IS_SYNC(inode))
sync_dirty_buffer(bh);
dquot_free_block_nodirty(inode, 1);
}
EXT2_I(inode)->i_file_acl = 0;
cleanup:
brelse(bh);
up_write(&EXT2_I(inode)->xattr_sem);
}
/*
* ext2_xattr_put_super()
*
* This is called when a file system is unmounted.
*/
void
ext2_xattr_put_super(struct super_block *sb)
{
mb_cache_shrink(sb->s_bdev);
}
/*
* ext2_xattr_cache_insert()
*
* Create a new entry in the extended attribute cache, and insert
* it unless such an entry is already in the cache.
*
* Returns 0, or a negative error number on failure.
*/
static int
ext2_xattr_cache_insert(struct buffer_head *bh)
{
__u32 hash = le32_to_cpu(HDR(bh)->h_hash);
struct mb_cache_entry *ce;
int error;
ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
if (!ce)
return -ENOMEM;
error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
if (error) {
mb_cache_entry_free(ce);
if (error == -EBUSY) {
ea_bdebug(bh, "already in cache (%d cache entries)",
atomic_read(&ext2_xattr_cache->c_entry_count));
error = 0;
}
} else {
ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
atomic_read(&ext2_xattr_cache->c_entry_count));
mb_cache_entry_release(ce);
}
return error;
}
/*
* ext2_xattr_cmp()
*
* 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
ext2_xattr_cmp(struct ext2_xattr_header *header1,
struct ext2_xattr_header *header2)
{
struct ext2_xattr_entry *entry1, *entry2;
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;
entry1 = EXT2_XATTR_NEXT(entry1);
entry2 = EXT2_XATTR_NEXT(entry2);
}
if (!IS_LAST_ENTRY(entry2))
return 1;
return 0;
}
/*
* ext2_xattr_cache_find()
*
* Find an identical extended attribute block.
*
* Returns a locked buffer head to the block found, or NULL if such
* a block was not found or an error occurred.
*/
static struct buffer_head *
ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
{
__u32 hash = le32_to_cpu(header->h_hash);
struct mb_cache_entry *ce;
if (!header->h_hash)
return NULL; /* never share */
ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
again:
ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
hash);
while (ce) {
struct buffer_head *bh;
if (IS_ERR(ce)) {
if (PTR_ERR(ce) == -EAGAIN)
goto again;
break;
}
bh = sb_bread(inode->i_sb, ce->e_block);
if (!bh) {
ext2_error(inode->i_sb, "ext2_xattr_cache_find",
"inode %ld: block %ld read error",
inode->i_ino, (unsigned long) ce->e_block);
} else {
lock_buffer(bh);
if (le32_to_cpu(HDR(bh)->h_refcount) >
EXT2_XATTR_REFCOUNT_MAX) {
ea_idebug(inode, "block %ld refcount %d>%d",
(unsigned long) ce->e_block,
le32_to_cpu(HDR(bh)->h_refcount),
EXT2_XATTR_REFCOUNT_MAX);
} else if (!ext2_xattr_cmp(header, HDR(bh))) {
ea_bdebug(bh, "b_count=%d",
atomic_read(&(bh->b_count)));
mb_cache_entry_release(ce);
return bh;
}
unlock_buffer(bh);
brelse(bh);
}
ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
}
return NULL;
}
#define NAME_HASH_SHIFT 5
#define VALUE_HASH_SHIFT 16
/*
* ext2_xattr_hash_entry()
*
* Compute the hash of an extended attribute.
*/
static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
struct ext2_xattr_entry *entry)
{
__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) +
EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
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
/*
* ext2_xattr_rehash()
*
* Re-compute the extended attribute hash value after an entry has changed.
*/
static void ext2_xattr_rehash(struct ext2_xattr_header *header,
struct ext2_xattr_entry *entry)
{
struct ext2_xattr_entry *here;
__u32 hash = 0;
ext2_xattr_hash_entry(header, entry);
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);
here = EXT2_XATTR_NEXT(here);
}
header->h_hash = cpu_to_le32(hash);
}
#undef BLOCK_HASH_SHIFT
int __init
init_ext2_xattr(void)
{
ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
if (!ext2_xattr_cache)
return -ENOMEM;
return 0;
}
void
exit_ext2_xattr(void)
{
mb_cache_destroy(ext2_xattr_cache);
}
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