--- /dev/null
+/*
+ * 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(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()
+ *
+ * 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);
+}
Code Review / kvmfornfv.git / blobdiff