diff options
Diffstat (limited to 'fs/ext4/xattr.c')
| -rw-r--r-- | fs/ext4/xattr.c | 1317 |
1 files changed, 1317 insertions, 0 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c new file mode 100644 index 00000000000..63233cd946a --- /dev/null +++ b/fs/ext4/xattr.c @@ -0,0 +1,1317 @@ +/* + * linux/fs/ext4/xattr.c + * + * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de> + * + * Fix by Harrison Xing <harrison@mountainviewdata.com>. + * Ext4 code with a lot of help from Eric Jarman <ejarman@acm.org>. + * 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 + * ---------------- + * EXT4_I(inode)->i_file_acl is protected by EXT4_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 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> +#include <linux/ext4_jbd2.h> +#include <linux/ext4_fs.h> +#include <linux/mbcache.h> +#include <linux/quotaops.h> +#include <linux/rwsem.h> +#include "xattr.h" +#include "acl.h" + +#define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data)) +#define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr)) +#define BFIRST(bh) ENTRY(BHDR(bh)+1) +#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) + +#define IHDR(inode, raw_inode) \ + ((struct ext4_xattr_ibody_header *) \ + ((void *)raw_inode + \ + EXT4_GOOD_OLD_INODE_SIZE + \ + EXT4_I(inode)->i_extra_isize)) +#define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1)) + +#ifdef EXT4_XATTR_DEBUG +# 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 + +static void ext4_xattr_cache_insert(struct buffer_head *); +static struct buffer_head *ext4_xattr_cache_find(struct inode *, + struct ext4_xattr_header *, + struct mb_cache_entry **); +static void ext4_xattr_rehash(struct ext4_xattr_header *, + struct ext4_xattr_entry *); + +static struct mb_cache *ext4_xattr_cache; + +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, +#endif + [EXT4_XATTR_INDEX_TRUSTED] = &ext4_xattr_trusted_handler, +#ifdef CONFIG_EXT4DEV_FS_SECURITY + [EXT4_XATTR_INDEX_SECURITY] = &ext4_xattr_security_handler, +#endif +}; + +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, +#endif +#ifdef CONFIG_EXT4DEV_FS_SECURITY + &ext4_xattr_security_handler, +#endif + NULL +}; + +static inline struct xattr_handler * +ext4_xattr_handler(int name_index) +{ + struct xattr_handler *handler = NULL; + + if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map)) + handler = ext4_xattr_handler_map[name_index]; + return handler; +} + +/* + * Inode operation listxattr() + * + * dentry->d_inode->i_mutex: don't care + */ +ssize_t +ext4_listxattr(struct dentry *dentry, char *buffer, size_t size) +{ + return ext4_xattr_list(dentry->d_inode, buffer, size); +} + +static int +ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end) +{ + while (!IS_LAST_ENTRY(entry)) { + struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry); + if ((void *)next >= end) + return -EIO; + entry = next; + } + return 0; +} + +static inline int +ext4_xattr_check_block(struct buffer_head *bh) +{ + int error; + + if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || + BHDR(bh)->h_blocks != cpu_to_le32(1)) + return -EIO; + error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size); + return error; +} + +static inline int +ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size) +{ + 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 +ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index, + const char *name, size_t size, int sorted) +{ + struct ext4_xattr_entry *entry; + size_t name_len; + int cmp = 1; + + if (name == NULL) + return -EINVAL; + name_len = strlen(name); + entry = *pentry; + for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) { + 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; + if (!cmp && ext4_xattr_check_entry(entry, size)) + return -EIO; + return cmp ? -ENODATA : 0; +} + +static int +ext4_xattr_block_get(struct inode *inode, int name_index, const char *name, + void *buffer, size_t buffer_size) +{ + struct buffer_head *bh = NULL; + struct ext4_xattr_entry *entry; + 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; + if (!EXT4_I(inode)->i_file_acl) + goto cleanup; + ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl); + bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); + if (!bh) + goto cleanup; + ea_bdebug(bh, "b_count=%d, refcount=%d", + atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount)); + if (ext4_xattr_check_block(bh)) { +bad_block: ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: bad block %llu", inode->i_ino, + EXT4_I(inode)->i_file_acl); + error = -EIO; + goto cleanup; + } + ext4_xattr_cache_insert(bh); + entry = BFIRST(bh); + error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1); + 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 +ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name, + void *buffer, size_t buffer_size) +{ + struct ext4_xattr_ibody_header *header; + struct ext4_xattr_entry *entry; + struct ext4_inode *raw_inode; + struct ext4_iloc iloc; + size_t size; + void *end; + int error; + + if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR)) + return -ENODATA; + error = ext4_get_inode_loc(inode, &iloc); + if (error) + return error; + raw_inode = ext4_raw_inode(&iloc); + header = IHDR(inode, raw_inode); + entry = IFIRST(header); + end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; + error = ext4_xattr_check_names(entry, end); + if (error) + goto cleanup; + error = ext4_xattr_find_entry(&entry, name_index, name, + 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; +} + +/* + * ext4_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 +ext4_xattr_get(struct inode *inode, int name_index, const char *name, + void *buffer, size_t buffer_size) +{ + int error; + + down_read(&EXT4_I(inode)->xattr_sem); + error = ext4_xattr_ibody_get(inode, name_index, name, buffer, + buffer_size); + if (error == -ENODATA) + error = ext4_xattr_block_get(inode, name_index, name, buffer, + buffer_size); + up_read(&EXT4_I(inode)->xattr_sem); + return error; +} + +static int +ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry, + char *buffer, size_t buffer_size) +{ + size_t rest = buffer_size; + + for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) { + struct xattr_handler *handler = + ext4_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) + return -ERANGE; + buffer += size; + } + rest -= size; + } + } + return buffer_size - rest; +} + +static int +ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size) +{ + struct buffer_head *bh = NULL; + int error; + + ea_idebug(inode, "buffer=%p, buffer_size=%ld", + buffer, (long)buffer_size); + + error = 0; + if (!EXT4_I(inode)->i_file_acl) + goto cleanup; + ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl); + bh = sb_bread(inode->i_sb, EXT4_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(BHDR(bh)->h_refcount)); + if (ext4_xattr_check_block(bh)) { + ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: bad block %llu", inode->i_ino, + EXT4_I(inode)->i_file_acl); + error = -EIO; + goto cleanup; + } + ext4_xattr_cache_insert(bh); + error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size); + +cleanup: + brelse(bh); + + return error; +} + +static int +ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size) +{ + struct ext4_xattr_ibody_header *header; + struct ext4_inode *raw_inode; + struct ext4_iloc iloc; + void *end; + int error; + + if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR)) + return 0; + error = ext4_get_inode_loc(inode, &iloc); + if (error) + return error; + raw_inode = ext4_raw_inode(&iloc); + header = IHDR(inode, raw_inode); + end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; + error = ext4_xattr_check_names(IFIRST(header), end); + if (error) + goto cleanup; + error = ext4_xattr_list_entries(inode, IFIRST(header), + buffer, buffer_size); + +cleanup: + brelse(iloc.bh); + return error; +} + +/* + * ext4_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. + */ +int +ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size) +{ + int i_error, b_error; + + down_read(&EXT4_I(inode)->xattr_sem); + i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size); + if (i_error < 0) { + b_error = 0; + } else { + if (buffer) { + buffer += i_error; + buffer_size -= i_error; + } + b_error = ext4_xattr_block_list(inode, buffer, buffer_size); + if (b_error < 0) + i_error = 0; + } + up_read(&EXT4_I(inode)->xattr_sem); + return i_error + b_error; +} + +/* + * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is + * not set, set it. + */ +static void ext4_xattr_update_super_block(handle_t *handle, + struct super_block *sb) +{ + if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR)) + return; + + lock_super(sb); + 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); + sb->s_dirt = 1; + ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh); + } + unlock_super(sb); +} + +/* + * Release the xattr block BH: If the reference count is > 1, decrement + * it; otherwise free the block. + */ +static void +ext4_xattr_release_block(handle_t *handle, struct inode *inode, + struct buffer_head *bh) +{ + struct mb_cache_entry *ce = NULL; + + ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr); + if (BHDR(bh)->h_refcount == cpu_to_le32(1)) { + ea_bdebug(bh, "refcount now=0; freeing"); + if (ce) + mb_cache_entry_free(ce); + ext4_free_blocks(handle, inode, bh->b_blocknr, 1); + get_bh(bh); + ext4_forget(handle, 1, inode, bh, bh->b_blocknr); + } else { + if (ext4_journal_get_write_access(handle, bh) == 0) { + lock_buffer(bh); + BHDR(bh)->h_refcount = cpu_to_le32( + le32_to_cpu(BHDR(bh)->h_refcount) - 1); + ext4_journal_dirty_metadata(handle, bh); + 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); + } +} + +struct ext4_xattr_info { + int name_index; + const char *name; + const void *value; + size_t value_len; +}; + +struct ext4_xattr_search { + struct ext4_xattr_entry *first; + void *base; + void *end; + struct ext4_xattr_entry *here; + int not_found; +}; + +static int +ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s) +{ + struct ext4_xattr_entry *last; + size_t free, min_offs = s->end - s->base, name_len = strlen(i->name); + + /* Compute min_offs and last. */ + last = s->first; + for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { + 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); + free += EXT4_XATTR_SIZE(size); + } + free += EXT4_XATTR_LEN(name_len); + } + if (i->value) { + if (free < EXT4_XATTR_SIZE(i->value_len) || + free < EXT4_XATTR_LEN(name_len) + + EXT4_XATTR_SIZE(i->value_len)) + return -ENOSPC; + } + + if (i->value && s->not_found) { + /* Insert the new name. */ + size_t size = EXT4_XATTR_LEN(name_len); + size_t rest = (void *)last - (void *)s->here + sizeof(__u32); + memmove((void *)s->here + size, s->here, rest); + memset(s->here, 0, size); + s->here->e_name_index = i->name_index; + s->here->e_name_len = name_len; + memcpy(s->here->e_name, i->name, name_len); + } else { + if (!s->here->e_value_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; + size_t size = EXT4_XATTR_SIZE( + le32_to_cpu(s->here->e_value_size)); + + if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) { + /* The old and the new value have the same + size. Just replace. */ + s->here->e_value_size = + cpu_to_le32(i->value_len); + memset(val + size - EXT4_XATTR_PAD, 0, + EXT4_XATTR_PAD); /* Clear pad bytes. */ + 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); + last = EXT4_XATTR_NEXT(last); + } + } + if (!i->value) { + /* Remove the old name. */ + size_t size = EXT4_XATTR_LEN(name_len); + last = ENTRY((void *)last - size); + memmove(s->here, (void *)s->here + size, + (void *)last - (void *)s->here + sizeof(__u32)); + memset(last, 0, size); + } + } + + if (i->value) { + /* Insert the new value. */ + s->here->e_value_size = cpu_to_le32(i->value_len); + if (i->value_len) { + size_t size = EXT4_XATTR_SIZE(i->value_len); + void *val = s->base + min_offs - size; + s->here->e_value_offs = cpu_to_le16(min_offs - size); + memset(val + size - EXT4_XATTR_PAD, 0, + EXT4_XATTR_PAD); /* Clear the pad bytes. */ + memcpy(val, i->value, i->value_len); + } + } + return 0; +} + +struct ext4_xattr_block_find { + struct ext4_xattr_search s; + struct buffer_head *bh; +}; + +static int +ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i, + struct ext4_xattr_block_find *bs) +{ + 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); + + if (EXT4_I(inode)->i_file_acl) { + /* The inode already has an extended attribute block. */ + bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl); + 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)); + if (ext4_xattr_check_block(bs->bh)) { + ext4_error(sb, __FUNCTION__, + "inode %lu: bad block %llu", inode->i_ino, + EXT4_I(inode)->i_file_acl); + 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; + error = ext4_xattr_find_entry(&bs->s.here, i->name_index, + 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 +ext4_xattr_block_set(handle_t *handle, struct inode *inode, + struct ext4_xattr_info *i, + struct ext4_xattr_block_find *bs) +{ + struct super_block *sb = inode->i_sb; + struct buffer_head *new_bh = NULL; + struct ext4_xattr_search *s = &bs->s; + struct mb_cache_entry *ce = NULL; + int error; + +#define header(x) ((struct ext4_xattr_header *)(x)) + + if (i->value && i->value_len > sb->s_blocksize) + return -ENOSPC; + if (s->base) { + ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev, + 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"); + error = ext4_journal_get_write_access(handle, bs->bh); + if (error) + goto cleanup; + lock_buffer(bs->bh); + error = ext4_xattr_set_entry(i, s); + if (!error) { + if (!IS_LAST_ENTRY(s->first)) + ext4_xattr_rehash(header(s->base), + s->here); + ext4_xattr_cache_insert(bs->bh); + } + unlock_buffer(bs->bh); + if (error == -EIO) + goto bad_block; + if (!error) + error = ext4_journal_dirty_metadata(handle, + 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); + header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC); + 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; + } + + error = ext4_xattr_set_entry(i, s); + if (error == -EIO) + goto bad_block; + if (error) + goto cleanup; + if (!IS_LAST_ENTRY(s->first)) + ext4_xattr_rehash(header(s->base), s->here); + +inserted: + if (!IS_LAST_ENTRY(s->first)) { + new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce); + 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; + error = ext4_journal_get_write_access(handle, + 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); + error = ext4_journal_dirty_metadata(handle, + 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 */ + 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, + goal, &error); + if (error) + goto cleanup; + ea_idebug(inode, "creating block %d", block); + + new_bh = sb_getblk(sb, block); + if (!new_bh) { +getblk_failed: + ext4_free_blocks(handle, inode, block, 1); + error = -EIO; + goto cleanup; + } + lock_buffer(new_bh); + error = ext4_journal_get_create_access(handle, new_bh); + 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); + ext4_xattr_cache_insert(new_bh); + error = ext4_journal_dirty_metadata(handle, new_bh); + if (error) + goto cleanup; + } + } + + /* Update the inode. */ + EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; + + /* Drop the previous xattr block. */ + if (bs->bh && bs->bh != new_bh) + ext4_xattr_release_block(handle, inode, bs->bh); + 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: + ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: bad block %llu", inode->i_ino, + EXT4_I(inode)->i_file_acl); + goto cleanup; + +#undef header +} + +struct ext4_xattr_ibody_find { + struct ext4_xattr_search s; + struct ext4_iloc iloc; +}; + +static int +ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i, + struct ext4_xattr_ibody_find *is) +{ + struct ext4_xattr_ibody_header *header; + struct ext4_inode *raw_inode; + int error; + + if (EXT4_I(inode)->i_extra_isize == 0) + return 0; + raw_inode = ext4_raw_inode(&is->iloc); + header = IHDR(inode, raw_inode); + is->s.base = is->s.first = IFIRST(header); + is->s.here = is->s.first; + 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); + if (error) + return error; + /* Find the named attribute. */ + error = ext4_xattr_find_entry(&is->s.here, i->name_index, + 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 +ext4_xattr_ibody_set(handle_t *handle, struct inode *inode, + struct ext4_xattr_info *i, + struct ext4_xattr_ibody_find *is) +{ + struct ext4_xattr_ibody_header *header; + struct ext4_xattr_search *s = &is->s; + int error; + + if (EXT4_I(inode)->i_extra_isize == 0) + return -ENOSPC; + error = ext4_xattr_set_entry(i, s); + if (error) + return error; + header = IHDR(inode, ext4_raw_inode(&is->iloc)); + if (!IS_LAST_ENTRY(s->first)) { + header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC); + EXT4_I(inode)->i_state |= EXT4_STATE_XATTR; + } else { + header->h_magic = cpu_to_le32(0); + EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR; + } + return 0; +} + +/* + * ext4_xattr_set_handle() + * + * 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 +ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index, + const char *name, const void *value, size_t value_len, + int flags) +{ + struct ext4_xattr_info i = { + .name_index = name_index, + .name = name, + .value = value, + .value_len = value_len, + + }; + struct ext4_xattr_ibody_find is = { + .s = { .not_found = -ENODATA, }, + }; + struct ext4_xattr_block_find bs = { + .s = { .not_found = -ENODATA, }, + }; + int error; + + if (!name) + return -EINVAL; + if (strlen(name) > 255) + return -ERANGE; + down_write(&EXT4_I(inode)->xattr_sem); + error = ext4_get_inode_loc(inode, &is.iloc); + if (error) + goto cleanup; + + 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; + } + + error = ext4_xattr_ibody_find(inode, &i, &is); + if (error) + goto cleanup; + if (is.s.not_found) + error = ext4_xattr_block_find(inode, &i, &bs); + 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; + } + error = ext4_journal_get_write_access(handle, is.iloc.bh); + if (error) + goto cleanup; + if (!value) { + if (!is.s.not_found) + error = ext4_xattr_ibody_set(handle, inode, &i, &is); + else if (!bs.s.not_found) + error = ext4_xattr_block_set(handle, inode, &i, &bs); + } else { + error = ext4_xattr_ibody_set(handle, inode, &i, &is); + if (!error && !bs.s.not_found) { + i.value = NULL; + error = ext4_xattr_block_set(handle, inode, &i, &bs); + } else if (error == -ENOSPC) { + error = ext4_xattr_block_set(handle, inode, &i, &bs); + if (error) + goto cleanup; + if (!is.s.not_found) { + i.value = NULL; + error = ext4_xattr_ibody_set(handle, inode, &i, + &is); + } + } + } + if (!error) { + ext4_xattr_update_super_block(handle, inode->i_sb); + inode->i_ctime = CURRENT_TIME_SEC; + error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); + /* + * The bh is consumed by ext4_mark_iloc_dirty, even with + * error != 0. + */ + is.iloc.bh = NULL; + if (IS_SYNC(inode)) + handle->h_sync = 1; + } + +cleanup: + brelse(is.iloc.bh); + brelse(bs.bh); + up_write(&EXT4_I(inode)->xattr_sem); + return error; +} + +/* + * ext4_xattr_set() + * + * Like ext4_xattr_set_handle, but start from an inode. This extended + * attribute modification is a filesystem transaction by itself. + * + * Returns 0, or a negative error number on failure. + */ +int +ext4_xattr_set(struct inode *inode, int name_index, const char *name, + const void *value, size_t value_len, int flags) +{ + handle_t *handle; + int error, retries = 0; + +retry: + handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); + if (IS_ERR(handle)) { + error = PTR_ERR(handle); + } else { + int error2; + + error = ext4_xattr_set_handle(handle, inode, name_index, name, + value, value_len, flags); + error2 = ext4_journal_stop(handle); + if (error == -ENOSPC && + ext4_should_retry_alloc(inode->i_sb, &retries)) + goto retry; + if (error == 0) + error = error2; + } + + return error; +} + +/* + * ext4_xattr_delete_inode() + * + * 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 +ext4_xattr_delete_inode(handle_t *handle, struct inode *inode) +{ + struct buffer_head *bh = NULL; + + if (!EXT4_I(inode)->i_file_acl) + goto cleanup; + bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); + if (!bh) { + ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: block %llu read error", inode->i_ino, + EXT4_I(inode)->i_file_acl); + goto cleanup; + } + if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || + BHDR(bh)->h_blocks != cpu_to_le32(1)) { + ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: bad block %llu", inode->i_ino, + EXT4_I(inode)->i_file_acl); + goto cleanup; + } + ext4_xattr_release_block(handle, inode, bh); + EXT4_I(inode)->i_file_acl = 0; + +cleanup: + brelse(bh); +} + +/* + * ext4_xattr_put_super() + * + * This is called when a file system is unmounted. + */ +void +ext4_xattr_put_super(struct super_block *sb) +{ + mb_cache_shrink(sb->s_bdev); +} + +/* + * ext4_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 void +ext4_xattr_cache_insert(struct buffer_head *bh) +{ + __u32 hash = le32_to_cpu(BHDR(bh)->h_hash); + struct mb_cache_entry *ce; + int error; + + ce = mb_cache_entry_alloc(ext4_xattr_cache); + 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); + } +} + +/* + * ext4_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 +ext4_xattr_cmp(struct ext4_xattr_header *header1, + struct ext4_xattr_header *header2) +{ + struct ext4_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 = EXT4_XATTR_NEXT(entry1); + entry2 = EXT4_XATTR_NEXT(entry2); + } + if (!IS_LAST_ENTRY(entry2)) + return 1; + return 0; +} + +/* + * ext4_xattr_cache_find() + * + * 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 * +ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header, + 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: + ce = mb_cache_entry_find_first(ext4_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) { + ext4_error(inode->i_sb, __FUNCTION__, + "inode %lu: block %lu read error", + inode->i_ino, (unsigned long) ce->e_block); + } else if (le32_to_cpu(BHDR(bh)->h_refcount) >= + EXT4_XATTR_REFCOUNT_MAX) { + ea_idebug(inode, "block %lu refcount %d>=%d", + (unsigned long) ce->e_block, + le32_to_cpu(BHDR(bh)->h_refcount), + EXT4_XATTR_REFCOUNT_MAX); + } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) { + *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 + +/* + * ext4_xattr_hash_entry() + * + * Compute the hash of an extended attribute. + */ +static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header, + struct ext4_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) + + EXT4_XATTR_ROUND) >> EXT4_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 + +/* + * ext4_xattr_rehash() + * + * Re-compute the extended attribute hash value after an entry has changed. + */ +static void ext4_xattr_rehash(struct ext4_xattr_header *header, + struct ext4_xattr_entry *entry) +{ + struct ext4_xattr_entry *here; + __u32 hash = 0; + + ext4_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 = EXT4_XATTR_NEXT(here); + } + header->h_hash = cpu_to_le32(hash); +} + +#undef BLOCK_HASH_SHIFT + +int __init +init_ext4_xattr(void) +{ + ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL, + sizeof(struct mb_cache_entry) + + sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6); + if (!ext4_xattr_cache) + return -ENOMEM; + return 0; +} + +void +exit_ext4_xattr(void) +{ + if (ext4_xattr_cache) + mb_cache_destroy(ext4_xattr_cache); + ext4_xattr_cache = NULL; +} |