Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1043 insertions, 0 deletions

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
new file mode 100644
index 000000000000..27982b500e84
--- /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);
+}