- 根目录:
- fs
- ext2
- xattr.c
/*
* 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 aligned 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/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] = &posix_acl_access_xattr_handler,
[EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_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
&posix_acl_access_xattr_handler,
&posix_acl_default_xattr_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;
name_len = strlen(name);
if (name_len > 255)
return -ERANGE;
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 */
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;
}
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 = d_inode(dentry);
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(handler, dentry, buffer,
rest, entry->e_name,
entry->e_name_len);
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()
*
* d_inode(dentry)->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);
mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
}
/*
* ext2_xattr_set()
*
* Create, replace or remove an extended attribute for this inode. Value
* 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 (unlikely(!new_bh)) {
ext2_free_blocks(inode, block, 1);
mark_inode_dirty(inode);
error = -ENOMEM;
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 = sync_inode_metadata(inode, 1);
/* 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);
}