diff options
Diffstat (limited to 'fs/ext2/xattr.c')
| -rw-r--r-- | fs/ext2/xattr.c | 1043 |
1 files changed, 1043 insertions, 0 deletions
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c new file mode 100644 index 0000000..27982b5 --- /dev/null +++ b/fs/ext2/xattr.c @@ -0,0 +1,1043 @@ +/* + * 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 "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 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 +}; + +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 struct xattr_handler * +ext2_xattr_handler(int name_index) +{ + 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 inode *inode, char *buffer, size_t buffer_size) +{ + 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)) { + struct xattr_handler *handler = + ext2_xattr_handler(entry->e_name_index); + + if (handler) { + size_t size = handler->list(inode, 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() + * + * dentry->d_inode->i_sem: don't care + */ +ssize_t +ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) +{ + return ext2_xattr_list(dentry->d_inode, 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; + + lock_super(sb); + EXT2_SB(sb)->s_es->s_feature_compat |= + cpu_to_le32(EXT2_FEATURE_COMPAT_EXT_ATTR); + sb->s_dirt = 1; + mark_buffer_dirty(EXT2_SB(sb)->s_sbh); + unlock_super(sb); +} + +/* + * 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 (IS_RDONLY(inode)) + return -EROFS; + if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) + return -EPERM; + 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 = kmalloc(sb->s_blocksize, GFP_KERNEL); + error = -ENOMEM; + if (header == NULL) + goto cleanup; + memset(header, 0, sb->s_blocksize); + 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 = -EDQUOT; + if (DQUOT_ALLOC_BLOCK(inode, 1)) { + unlock_buffer(new_bh); + goto cleanup; + } + HDR(new_bh)->h_refcount = cpu_to_le32(1 + + le32_to_cpu(HDR(new_bh)->h_refcount)); + 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 */ + int goal = le32_to_cpu(EXT2_SB(sb)->s_es-> + s_first_data_block) + + EXT2_I(inode)->i_block_group * + EXT2_BLOCKS_PER_GROUP(sb); + int block = ext2_new_block(inode, goal, + NULL, NULL, &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); + 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(inode, 1); + 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); + /* 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. */ + HDR(old_bh)->h_refcount = cpu_to_le32( + le32_to_cpu(HDR(old_bh)->h_refcount) - 1); + if (ce) + mb_cache_entry_release(ce); + DQUOT_FREE_BLOCK(inode, 1); + 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); + } else { + HDR(bh)->h_refcount = cpu_to_le32( + le32_to_cpu(HDR(bh)->h_refcount) - 1); + if (ce) + mb_cache_entry_release(ce); + mark_buffer_dirty(bh); + if (IS_SYNC(inode)) + sync_dirty_buffer(bh); + DQUOT_FREE_BLOCK(inode, 1); + } + ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount) - 1); + unlock_buffer(bh); + 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(ext2_xattr_cache, 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); + 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, 0, + 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, 0, 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", NULL, + sizeof(struct mb_cache_entry) + + sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6); + if (!ext2_xattr_cache) + return -ENOMEM; + return 0; +} + +void +exit_ext2_xattr(void) +{ + mb_cache_destroy(ext2_xattr_cache); +} |
