ClabureDB: Classified Bug-Reports Database

   /*
    * linux/fs/reiserfs/xattr.c
    *
    * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com>
    *
    */
   
   /*
    * In order to implement EA/ACLs in a clean, backwards compatible manner,
   * they are implemented as files in a "private" directory.
   * Each EA is in it's own file, with the directory layout like so (/ is assumed
   * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory,
   * directories named using the capital-hex form of the objectid and
   * generation number are used. Inside each directory are individual files
   * named with the name of the extended attribute.
   *
   * So, for objectid 12648430, we could have:
   * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access
   * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default
   * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type
   * .. or similar.
   *
   * The file contents are the text of the EA. The size is known based on the
   * stat data describing the file.
   *
   * In the case of system.posix_acl_access and system.posix_acl_default, since
   * these are special cases for filesystem ACLs, they are interpreted by the
   * kernel, in addition, they are negatively and positively cached and attached
   * to the inode so that unnecessary lookups are avoided.
   */
  
  #include <linux/reiserfs_fs.h>
  #include <linux/capability.h>
  #include <linux/dcache.h>
  #include <linux/namei.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/file.h>
  #include <linux/pagemap.h>
  #include <linux/xattr.h>
  #include <linux/reiserfs_xattr.h>
  #include <linux/reiserfs_acl.h>
  #include <asm/uaccess.h>
  #include <net/checksum.h>
  #include <linux/smp_lock.h>
  #include <linux/stat.h>
  
  #define FL_READONLY 128
  #define FL_DIR_SEM_HELD 256
  #define PRIVROOT_NAME ".reiserfs_priv"
  #define XAROOT_NAME   "xattrs"
  
  static struct reiserfs_xattr_handler *find_xattr_handler_prefix(const char
                                                                  *prefix);
  
  /* Returns the dentry referring to the root of the extended attribute
   * directory tree. If it has already been retrieved, it is used. If it
   * hasn't been created and the flags indicate creation is allowed, we
   * attempt to create it. On error, we return a pointer-encoded error.
   */
  static struct dentry *get_xa_root(struct super_block *sb, int flags)
  {
          struct dentry *privroot = dget(REISERFS_SB(sb)->priv_root);
          struct dentry *xaroot;
  
          /* This needs to be created at mount-time */
          if (!privroot)
                  return ERR_PTR(-ENODATA);
  
          mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
          if (REISERFS_SB(sb)->xattr_root) {
                  xaroot = dget(REISERFS_SB(sb)->xattr_root);
                  goto out;
          }
  
          xaroot = lookup_one_len(XAROOT_NAME, privroot, strlen(XAROOT_NAME));
          if (IS_ERR(xaroot)) {
                  goto out;
          } else if (!xaroot->d_inode) {
                  int err = -ENODATA;
                  if (flags == 0 || flags & XATTR_CREATE)
                          err = privroot->d_inode->i_op->mkdir(privroot->d_inode,
                                                               xaroot, 0700);
                  if (err) {
                          dput(xaroot);
                          xaroot = ERR_PTR(err);
                          goto out;
                  }
          }
          REISERFS_SB(sb)->xattr_root = dget(xaroot);
  
        out:
          mutex_unlock(&privroot->d_inode->i_mutex);
          dput(privroot);
          return xaroot;
  }
  
  /* Opens the directory corresponding to the inode's extended attribute store.
   * If flags allow, the tree to the directory may be created. If creation is
  * prohibited, -ENODATA is returned. */
 static struct dentry *open_xa_dir(const struct inode *inode, int flags)
 {
         struct dentry *xaroot, *xadir;
         char namebuf[17];
 
         xaroot = get_xa_root(inode->i_sb, flags);
         if (IS_ERR(xaroot))
                 return xaroot;
 
         /* ok, we have xaroot open */
         snprintf(namebuf, sizeof(namebuf), "%X.%X",
                  le32_to_cpu(INODE_PKEY(inode)->k_objectid),
                  inode->i_generation);
         xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
         if (IS_ERR(xadir)) {
                 dput(xaroot);
                 return xadir;
         }
 
         if (!xadir->d_inode) {
                 int err;
                 if (flags == 0 || flags & XATTR_CREATE) {
                         /* Although there is nothing else trying to create this directory,
                          * another directory with the same hash may be created, so we need
                          * to protect against that */
                         err =
                             xaroot->d_inode->i_op->mkdir(xaroot->d_inode, xadir,
                                                          0700);
                         if (err) {
                                 dput(xaroot);
                                 dput(xadir);
                                 return ERR_PTR(err);
                         }
                 }
                 if (!xadir->d_inode) {
                         dput(xaroot);
                         dput(xadir);
                         return ERR_PTR(-ENODATA);
                 }
         }
 
         dput(xaroot);
         return xadir;
 }
 
 /* Returns a dentry corresponding to a specific extended attribute file
  * for the inode. If flags allow, the file is created. Otherwise, a
  * valid or negative dentry, or an error is returned. */
 static struct dentry *get_xa_file_dentry(const struct inode *inode,
                                          const char *name, int flags)
 {
         struct dentry *xadir, *xafile;
         int err = 0;
 
         xadir = open_xa_dir(inode, flags);
         if (IS_ERR(xadir)) {
                 return ERR_CAST(xadir);
         } else if (!xadir->d_inode) {
                 dput(xadir);
                 return ERR_PTR(-ENODATA);
         }
 
         xafile = lookup_one_len(name, xadir, strlen(name));
         if (IS_ERR(xafile)) {
                 dput(xadir);
                 return ERR_CAST(xafile);
         }
 
         if (xafile->d_inode) {        /* file exists */
                 if (flags & XATTR_CREATE) {
                         err = -EEXIST;
                         dput(xafile);
                         goto out;
                 }
         } else if (flags & XATTR_REPLACE || flags & FL_READONLY) {
                 goto out;
         } else {
                 /* inode->i_mutex is down, so nothing else can try to create
                  * the same xattr */
                 err = xadir->d_inode->i_op->create(xadir->d_inode, xafile,
                                                    0700 | S_IFREG, NULL);
 
                 if (err) {
                         dput(xafile);
                         goto out;
                 }
         }
 
       out:
         dput(xadir);
         if (err)
                 xafile = ERR_PTR(err);
         else if (!xafile->d_inode) {
                 dput(xafile);
                 xafile = ERR_PTR(-ENODATA);
         }
         return xafile;
 }
 
 /*
  * this is very similar to fs/reiserfs/dir.c:reiserfs_readdir, but
  * we need to drop the path before calling the filldir struct.  That
  * would be a big performance hit to the non-xattr case, so I've copied
  * the whole thing for now. --clm
  *
  * the big difference is that I go backwards through the directory,
  * and don't mess with f->f_pos, but the idea is the same.  Do some
  * action on each and every entry in the directory.
  *
  * we're called with i_mutex held, so there are no worries about the directory
  * changing underneath us.
  */
 static int __xattr_readdir(struct inode *inode, void *dirent, filldir_t filldir)
 {
         struct cpu_key pos_key;        /* key of current position in the directory (key of directory entry) */
         INITIALIZE_PATH(path_to_entry);
         struct buffer_head *bh;
         int entry_num;
         struct item_head *ih, tmp_ih;
         int search_res;
         char *local_buf;
         loff_t next_pos;
         char small_buf[32];        /* avoid kmalloc if we can */
         struct reiserfs_de_head *deh;
         int d_reclen;
         char *d_name;
         off_t d_off;
         ino_t d_ino;
         struct reiserfs_dir_entry de;
 
         /* form key for search the next directory entry using f_pos field of
            file structure */
         next_pos = max_reiserfs_offset(inode);
 
         while (1) {
               research:
                 if (next_pos <= DOT_DOT_OFFSET)
                         break;
                 make_cpu_key(&pos_key, inode, next_pos, TYPE_DIRENTRY, 3);
 
                 search_res =
                     search_by_entry_key(inode->i_sb, &pos_key, &path_to_entry,
                                         &de);
                 if (search_res == IO_ERROR) {
                         // FIXME: we could just skip part of directory which could
                         // not be read
                         pathrelse(&path_to_entry);
                         return -EIO;
                 }
 
                 if (search_res == NAME_NOT_FOUND)
                         de.de_entry_num--;
 
                 set_de_name_and_namelen(&de);
                 entry_num = de.de_entry_num;
                 deh = &(de.de_deh[entry_num]);
 
                 bh = de.de_bh;
                 ih = de.de_ih;
 
                 if (!is_direntry_le_ih(ih)) {
                         reiserfs_warning(inode->i_sb, "not direntry %h", ih);
                         break;
                 }
                 copy_item_head(&tmp_ih, ih);
 
                 /* we must have found item, that is item of this directory, */
                 RFALSE(COMP_SHORT_KEYS(&(ih->ih_key), &pos_key),
                        "vs-9000: found item %h does not match to dir we readdir %K",
                        ih, &pos_key);
 
                 if (deh_offset(deh) <= DOT_DOT_OFFSET) {
                         break;
                 }
 
                 /* look for the previous entry in the directory */
                 next_pos = deh_offset(deh) - 1;
 
                 if (!de_visible(deh))
                         /* it is hidden entry */
                         continue;
 
                 d_reclen = entry_length(bh, ih, entry_num);
                 d_name = B_I_DEH_ENTRY_FILE_NAME(bh, ih, deh);
                 d_off = deh_offset(deh);
                 d_ino = deh_objectid(deh);
 
                 if (!d_name[d_reclen - 1])
                         d_reclen = strlen(d_name);
 
                 if (d_reclen > REISERFS_MAX_NAME(inode->i_sb->s_blocksize)) {
                         /* too big to send back to VFS */
                         continue;
                 }
 
                 /* Ignore the .reiserfs_priv entry */
                 if (reiserfs_xattrs(inode->i_sb) &&
                     !old_format_only(inode->i_sb) &&
                     deh_objectid(deh) ==
                     le32_to_cpu(INODE_PKEY
                                 (REISERFS_SB(inode->i_sb)->priv_root->d_inode)->
                                 k_objectid))
                         continue;
 
                 if (d_reclen <= 32) {
                         local_buf = small_buf;
                 } else {
                         local_buf = kmalloc(d_reclen, GFP_NOFS);
                         if (!local_buf) {
                                 pathrelse(&path_to_entry);
                                 return -ENOMEM;
                         }
                         if (item_moved(&tmp_ih, &path_to_entry)) {
                                 kfree(local_buf);
 
                                 /* sigh, must retry.  Do this same offset again */
                                 next_pos = d_off;
                                 goto research;
                         }
                 }
 
                 // Note, that we copy name to user space via temporary
                 // buffer (local_buf) because filldir will block if
                 // user space buffer is swapped out. At that time
                 // entry can move to somewhere else
                 memcpy(local_buf, d_name, d_reclen);
 
                 /* the filldir function might need to start transactions,
                  * or do who knows what.  Release the path now that we've
                  * copied all the important stuff out of the deh
                  */
                 pathrelse(&path_to_entry);
 
                 if (filldir(dirent, local_buf, d_reclen, d_off, d_ino,
                             DT_UNKNOWN) < 0) {
                         if (local_buf != small_buf) {
                                 kfree(local_buf);
                         }
                         goto end;
                 }
                 if (local_buf != small_buf) {
                         kfree(local_buf);
                 }
         }                        /* while */
 
       end:
         pathrelse(&path_to_entry);
         return 0;
 }
 
 /*
  * this could be done with dedicated readdir ops for the xattr files,
  * but I want to get something working asap
  * this is stolen from vfs_readdir
  *
  */
 static
 int xattr_readdir(struct inode *inode, filldir_t filler, void *buf)
 {
         int res = -ENOENT;
         mutex_lock_nested(&inode->i_mutex, I_MUTEX_XATTR);
         if (!IS_DEADDIR(inode)) {
                 lock_kernel();
                 res = __xattr_readdir(inode, buf, filler);
                 unlock_kernel();
         }
         mutex_unlock(&inode->i_mutex);
         return res;
 }
 
 /* Internal operations on file data */
 static inline void reiserfs_put_page(struct page *page)
 {
         kunmap(page);
         page_cache_release(page);
 }
 
 static struct page *reiserfs_get_page(struct inode *dir, unsigned long n)
 {
         struct address_space *mapping = dir->i_mapping;
         struct page *page;
         /* We can deadlock if we try to free dentries,
            and an unlink/rmdir has just occured - GFP_NOFS avoids this */
         mapping_set_gfp_mask(mapping, GFP_NOFS);
         page = read_mapping_page(mapping, n, NULL);
         if (!IS_ERR(page)) {
                 kmap(page);
                 if (PageError(page))
                         goto fail;
         }
         return page;
 
       fail:
         reiserfs_put_page(page);
         return ERR_PTR(-EIO);
 }
 
 static inline __u32 xattr_hash(const char *msg, int len)
 {
         return csum_partial(msg, len, 0);
 }
 
 int reiserfs_commit_write(struct file *f, struct page *page,
                           unsigned from, unsigned to);
 int reiserfs_prepare_write(struct file *f, struct page *page,
                            unsigned from, unsigned to);
 
 
 /* Generic extended attribute operations that can be used by xa plugins */
 
 /*
  * inode->i_mutex: down
  */
 int
 reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
                    size_t buffer_size, int flags)
 {
         int err = 0;
         struct dentry *dentry;
         struct page *page;
         char *data;
         struct address_space *mapping;
         size_t file_pos = 0;
         size_t buffer_pos = 0;
         struct inode *xinode;
         struct iattr newattrs;
         __u32 xahash = 0;
 
         if (get_inode_sd_version(inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
         /* Empty xattrs are ok, they're just empty files, no hash */
         if (buffer && buffer_size)
                 xahash = xattr_hash(buffer, buffer_size);
 
       open_file:
         dentry = get_xa_file_dentry(inode, name, flags);
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
                 goto out;
         }
 
         xinode = dentry->d_inode;
         REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 
         /* we need to copy it off.. */
         if (xinode->i_nlink > 1) {
                 dput(dentry);
                 err = reiserfs_xattr_del(inode, name);
                 if (err < 0)
                         goto out;
                 /* We just killed the old one, we're not replacing anymore */
                 if (flags & XATTR_REPLACE)
                         flags &= ~XATTR_REPLACE;
                 goto open_file;
         }
 
         /* Resize it so we're ok to write there */
         newattrs.ia_size = buffer_size;
         newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
         mutex_lock_nested(&xinode->i_mutex, I_MUTEX_XATTR);
         err = notify_change(dentry, &newattrs);
         if (err)
                 goto out_filp;
 
         mapping = xinode->i_mapping;
         while (buffer_pos < buffer_size || buffer_pos == 0) {
                 size_t chunk;
                 size_t skip = 0;
                 size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1));
                 if (buffer_size - buffer_pos > PAGE_CACHE_SIZE)
                         chunk = PAGE_CACHE_SIZE;
                 else
                         chunk = buffer_size - buffer_pos;
 
                 page = reiserfs_get_page(xinode, file_pos >> PAGE_CACHE_SHIFT);
                 if (IS_ERR(page)) {
                         err = PTR_ERR(page);
                         goto out_filp;
                 }
 
                 lock_page(page);
                 data = page_address(page);
 
                 if (file_pos == 0) {
                         struct reiserfs_xattr_header *rxh;
                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
                         if (chunk + skip > PAGE_CACHE_SIZE)
                                 chunk = PAGE_CACHE_SIZE - skip;
                         rxh = (struct reiserfs_xattr_header *)data;
                         rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
                         rxh->h_hash = cpu_to_le32(xahash);
                 }
 
                 err = reiserfs_prepare_write(NULL, page, page_offset,
                                             page_offset + chunk + skip);
                 if (!err) {
                         if (buffer)
                                 memcpy(data + skip, buffer + buffer_pos, chunk);
                         err = reiserfs_commit_write(NULL, page, page_offset,
                                                     page_offset + chunk +
                                                     skip);
                 }
                 unlock_page(page);
                 reiserfs_put_page(page);
                 buffer_pos += chunk;
                 file_pos += chunk;
                 skip = 0;
                 if (err || buffer_size == 0 || !buffer)
                         break;
         }
 
         /* We can't mark the inode dirty if it's not hashed. This is the case
          * when we're inheriting the default ACL. If we dirty it, the inode
          * gets marked dirty, but won't (ever) make it onto the dirty list until
          * it's synced explicitly to clear I_DIRTY. This is bad. */
         if (!hlist_unhashed(&inode->i_hash)) {
                 inode->i_ctime = CURRENT_TIME_SEC;
                 mark_inode_dirty(inode);
         }
 
       out_filp:
         mutex_unlock(&xinode->i_mutex);
         dput(dentry);
 
       out:
         return err;
 }
 
 /*
  * inode->i_mutex: down
  */
 int
 reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
                    size_t buffer_size)
 {
         ssize_t err = 0;
         struct dentry *dentry;
         size_t isize;
         size_t file_pos = 0;
         size_t buffer_pos = 0;
         struct page *page;
         struct inode *xinode;
         __u32 hash = 0;
 
         if (name == NULL)
                 return -EINVAL;
 
         /* We can't have xattrs attached to v1 items since they don't have
          * generation numbers */
         if (get_inode_sd_version(inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
         dentry = get_xa_file_dentry(inode, name, FL_READONLY);
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
                 goto out;
         }
 
         xinode = dentry->d_inode;
         isize = xinode->i_size;
         REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 
         /* Just return the size needed */
         if (buffer == NULL) {
                 err = isize - sizeof(struct reiserfs_xattr_header);
                 goto out_dput;
         }
 
         if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
                 err = -ERANGE;
                 goto out_dput;
         }
 
         while (file_pos < isize) {
                 size_t chunk;
                 char *data;
                 size_t skip = 0;
                 if (isize - file_pos > PAGE_CACHE_SIZE)
                         chunk = PAGE_CACHE_SIZE;
                 else
                         chunk = isize - file_pos;
 
                 page = reiserfs_get_page(xinode, file_pos >> PAGE_CACHE_SHIFT);
                 if (IS_ERR(page)) {
                         err = PTR_ERR(page);
                         goto out_dput;
                 }
 
                 lock_page(page);
                 data = page_address(page);
                 if (file_pos == 0) {
                         struct reiserfs_xattr_header *rxh =
                             (struct reiserfs_xattr_header *)data;
                         skip = file_pos = sizeof(struct reiserfs_xattr_header);
                         chunk -= skip;
                         /* Magic doesn't match up.. */
                         if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
                                 unlock_page(page);
                                 reiserfs_put_page(page);
                                 reiserfs_warning(inode->i_sb,
                                                  "Invalid magic for xattr (%s) "
                                                  "associated with %k", name,
                                                  INODE_PKEY(inode));
                                 err = -EIO;
                                 goto out_dput;
                         }
                         hash = le32_to_cpu(rxh->h_hash);
                 }
                 memcpy(buffer + buffer_pos, data + skip, chunk);
                 unlock_page(page);
                 reiserfs_put_page(page);
                 file_pos += chunk;
                 buffer_pos += chunk;
                 skip = 0;
         }
         err = isize - sizeof(struct reiserfs_xattr_header);
 
         if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
             hash) {
                 reiserfs_warning(inode->i_sb,
                                  "Invalid hash for xattr (%s) associated "
                                  "with %k", name, INODE_PKEY(inode));
                 err = -EIO;
         }
 
       out_dput:
         dput(dentry);
 
       out:
         return err;
 }
 
 static int
 __reiserfs_xattr_del(struct dentry *xadir, const char *name, int namelen)
 {
         struct dentry *dentry;
         struct inode *dir = xadir->d_inode;
         int err = 0;
 
         dentry = lookup_one_len(name, xadir, namelen);
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
                 goto out;
         } else if (!dentry->d_inode) {
                 err = -ENODATA;
                 goto out_file;
         }
 
         /* Skip directories.. */
         if (S_ISDIR(dentry->d_inode->i_mode))
                 goto out_file;
 
         if (!is_reiserfs_priv_object(dentry->d_inode)) {
                 reiserfs_warning(dir->i_sb, "OID %08x [%.*s/%.*s] doesn't have "
                                  "priv flag set [parent is %sset].",
                                  le32_to_cpu(INODE_PKEY(dentry->d_inode)->
                                              k_objectid), xadir->d_name.len,
                                  xadir->d_name.name, namelen, name,
                                  is_reiserfs_priv_object(xadir->
                                                          d_inode) ? "" :
                                  "not ");
                 dput(dentry);
                 return -EIO;
         }
 
         err = dir->i_op->unlink(dir, dentry);
         if (!err)
                 d_delete(dentry);
 
       out_file:
         dput(dentry);
 
       out:
         return err;
 }
 
 int reiserfs_xattr_del(struct inode *inode, const char *name)
 {
         struct dentry *dir;
         int err;
 
         dir = open_xa_dir(inode, FL_READONLY);
         if (IS_ERR(dir)) {
                 err = PTR_ERR(dir);
                 goto out;
         }
 
         err = __reiserfs_xattr_del(dir, name, strlen(name));
         dput(dir);
 
         if (!err) {
                 inode->i_ctime = CURRENT_TIME_SEC;
                 mark_inode_dirty(inode);
         }
 
       out:
         return err;
 }
 
 /* The following are side effects of other operations that aren't explicitly
  * modifying extended attributes. This includes operations such as permissions
  * or ownership changes, object deletions, etc. */
 
 static int
 reiserfs_delete_xattrs_filler(void *buf, const char *name, int namelen,
                               loff_t offset, u64 ino, unsigned int d_type)
 {
         struct dentry *xadir = (struct dentry *)buf;
 
         return __reiserfs_xattr_del(xadir, name, namelen);
 
 }
 
 /* This is called w/ inode->i_mutex downed */
 int reiserfs_delete_xattrs(struct inode *inode)
 {
         struct dentry *dir, *root;
         int err = 0;
 
         /* Skip out, an xattr has no xattrs associated with it */
         if (is_reiserfs_priv_object(inode) ||
             get_inode_sd_version(inode) == STAT_DATA_V1 ||
             !reiserfs_xattrs(inode->i_sb)) {
                 return 0;
         }
         reiserfs_read_lock_xattrs(inode->i_sb);
         dir = open_xa_dir(inode, FL_READONLY);
         reiserfs_read_unlock_xattrs(inode->i_sb);
         if (IS_ERR(dir)) {
                 err = PTR_ERR(dir);
                 goto out;
         } else if (!dir->d_inode) {
                 dput(dir);
                 return 0;
         }
 
         lock_kernel();
         err = xattr_readdir(dir->d_inode, reiserfs_delete_xattrs_filler, dir);
         if (err) {
                 unlock_kernel();
                 goto out_dir;
         }
 
         /* Leftovers besides . and .. -- that's not good. */
         if (dir->d_inode->i_nlink <= 2) {
                 root = get_xa_root(inode->i_sb, XATTR_REPLACE);
                 reiserfs_write_lock_xattrs(inode->i_sb);
                 err = vfs_rmdir(root->d_inode, dir);
                 reiserfs_write_unlock_xattrs(inode->i_sb);
                 dput(root);
         } else {
                 reiserfs_warning(inode->i_sb,
                                  "Couldn't remove all entries in directory");
         }
         unlock_kernel();
 
       out_dir:
         dput(dir);
 
       out:
         if (!err)
                 REISERFS_I(inode)->i_flags =
                     REISERFS_I(inode)->i_flags & ~i_has_xattr_dir;
         return err;
 }
 
 struct reiserfs_chown_buf {
         struct inode *inode;
         struct dentry *xadir;
         struct iattr *attrs;
 };
 
 /* XXX: If there is a better way to do this, I'd love to hear about it */
 static int
 reiserfs_chown_xattrs_filler(void *buf, const char *name, int namelen,
                              loff_t offset, u64 ino, unsigned int d_type)
 {
         struct reiserfs_chown_buf *chown_buf = (struct reiserfs_chown_buf *)buf;
         struct dentry *xafile, *xadir = chown_buf->xadir;
         struct iattr *attrs = chown_buf->attrs;
         int err = 0;
 
         xafile = lookup_one_len(name, xadir, namelen);
         if (IS_ERR(xafile))
                 return PTR_ERR(xafile);
         else if (!xafile->d_inode) {
                 dput(xafile);
                 return -ENODATA;
         }
 
         if (!S_ISDIR(xafile->d_inode->i_mode))
                 err = notify_change(xafile, attrs);
         dput(xafile);
 
         return err;
 }
 
 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
 {
         struct dentry *dir;
         int err = 0;
         struct reiserfs_chown_buf buf;
         unsigned int ia_valid = attrs->ia_valid;
 
         /* Skip out, an xattr has no xattrs associated with it */
         if (is_reiserfs_priv_object(inode) ||
             get_inode_sd_version(inode) == STAT_DATA_V1 ||
             !reiserfs_xattrs(inode->i_sb)) {
                 return 0;
         }
         reiserfs_read_lock_xattrs(inode->i_sb);
         dir = open_xa_dir(inode, FL_READONLY);
         reiserfs_read_unlock_xattrs(inode->i_sb);
         if (IS_ERR(dir)) {
                 if (PTR_ERR(dir) != -ENODATA)
                         err = PTR_ERR(dir);
                 goto out;
         } else if (!dir->d_inode) {
                 dput(dir);
                 goto out;
         }
 
         lock_kernel();
 
         attrs->ia_valid &= (ATTR_UID | ATTR_GID | ATTR_CTIME);
         buf.xadir = dir;
         buf.attrs = attrs;
         buf.inode = inode;
 
         err = xattr_readdir(dir->d_inode, reiserfs_chown_xattrs_filler, &buf);
         if (err) {
                 unlock_kernel();
                 goto out_dir;
         }
 
         err = notify_change(dir, attrs);
         unlock_kernel();
 
       out_dir:
         dput(dir);
 
       out:
         attrs->ia_valid = ia_valid;
         return err;
 }
 
 /* Actual operations that are exported to VFS-land */
 
 /*
  * Inode operation getxattr()
  * Preliminary locking: we down dentry->d_inode->i_mutex
  */
 ssize_t
 reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer,
                   size_t size)
 {
         struct reiserfs_xattr_handler *xah = find_xattr_handler_prefix(name);
         int err;
 
         if (!xah || !reiserfs_xattrs(dentry->d_sb) ||
             get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
         reiserfs_read_lock_xattr_i(dentry->d_inode);
         reiserfs_read_lock_xattrs(dentry->d_sb);
         err = xah->get(dentry->d_inode, name, buffer, size);
         reiserfs_read_unlock_xattrs(dentry->d_sb);
         reiserfs_read_unlock_xattr_i(dentry->d_inode);
         return err;
 }
 
 /*
  * Inode operation setxattr()
  *
  * dentry->d_inode->i_mutex down
  */
 int
 reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value,
                   size_t size, int flags)
 {
         struct reiserfs_xattr_handler *xah = find_xattr_handler_prefix(name);
         int err;
         int lock;
 
         if (!xah || !reiserfs_xattrs(dentry->d_sb) ||
             get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
         reiserfs_write_lock_xattr_i(dentry->d_inode);
         lock = !has_xattr_dir(dentry->d_inode);
         if (lock)
                 reiserfs_write_lock_xattrs(dentry->d_sb);
         else
                 reiserfs_read_lock_xattrs(dentry->d_sb);
         err = xah->set(dentry->d_inode, name, value, size, flags);
         if (lock)
                 reiserfs_write_unlock_xattrs(dentry->d_sb);
         else
                 reiserfs_read_unlock_xattrs(dentry->d_sb);
         reiserfs_write_unlock_xattr_i(dentry->d_inode);
         return err;
 }
 
 /*
  * Inode operation removexattr()
  *
  * dentry->d_inode->i_mutex down
  */
 int reiserfs_removexattr(struct dentry *dentry, const char *name)
 {
         int err;
         struct reiserfs_xattr_handler *xah = find_xattr_handler_prefix(name);
 
         if (!xah || !reiserfs_xattrs(dentry->d_sb) ||
             get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
         reiserfs_write_lock_xattr_i(dentry->d_inode);
         reiserfs_read_lock_xattrs(dentry->d_sb);
 
         /* Deletion pre-operation */
         if (xah->del) {
                 err = xah->del(dentry->d_inode, name);
                 if (err)
                         goto out;
         }
 
         err = reiserfs_xattr_del(dentry->d_inode, name);
 
         dentry->d_inode->i_ctime = CURRENT_TIME_SEC;
         mark_inode_dirty(dentry->d_inode);
 
       out:
         reiserfs_read_unlock_xattrs(dentry->d_sb);
         reiserfs_write_unlock_xattr_i(dentry->d_inode);
         return err;
 }
 
 /* This is what filldir will use:
  * r_pos will always contain the amount of space required for the entire
  * list. If r_pos becomes larger than r_size, we need more space and we
  * return an error indicating this. If r_pos is less than r_size, then we've
  * filled the buffer successfully and we return success */
 struct reiserfs_listxattr_buf {
         int r_pos;
         int r_size;
         char *r_buf;
         struct inode *r_inode;
 };
 
 static int
 reiserfs_listxattr_filler(void *buf, const char *name, int namelen,
                           loff_t offset, u64 ino, unsigned int d_type)
 {
         struct reiserfs_listxattr_buf *b = (struct reiserfs_listxattr_buf *)buf;
         int len = 0;
         if (name[0] != '.'
             || (namelen != 1 && (name[1] != '.' || namelen != 2))) {
                 struct reiserfs_xattr_handler *xah =
                     find_xattr_handler_prefix(name);
                 if (!xah)
                         return 0;        /* Unsupported xattr name, skip it */
 
                 /* We call ->list() twice because the operation isn't required to just
                  * return the name back - we want to make sure we have enough space */
                 len += xah->list(b->r_inode, name, namelen, NULL);
 
                 if (len) {
                         if (b->r_pos + len + 1 <= b->r_size) {
                                 char *p = b->r_buf + b->r_pos;
                                 p += xah->list(b->r_inode, name, namelen, p);
                                 *p++ = '\0';
                         }
                         b->r_pos += len + 1;
                 }
         }
 
         return 0;
 }
 
 /*
  * Inode operation listxattr()
  *
  * Preliminary locking: we down dentry->d_inode->i_mutex
  */
 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
 {
         struct dentry *dir;
         int err = 0;
         struct reiserfs_listxattr_buf buf;
 
         if (!dentry->d_inode)
                 return -EINVAL;
 
         if (!reiserfs_xattrs(dentry->d_sb) ||
             get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                 return -EOPNOTSUPP;
 
        reiserfs_read_lock_xattr_i(dentry->d_inode);
        reiserfs_read_lock_xattrs(dentry->d_sb);
        dir = open_xa_dir(dentry->d_inode, FL_READONLY);
        reiserfs_read_unlock_xattrs(dentry->d_sb);
        if (IS_ERR(dir)) {
                err = PTR_ERR(dir);
                if (err == -ENODATA)
                        err = 0;        /* Not an error if there aren't any xattrs */
                goto out;
        }

        buf.r_buf = buffer;
        buf.r_size = buffer ? size : 0;
        buf.r_pos = 0;
        buf.r_inode = dentry->d_inode;

        REISERFS_I(dentry->d_inode)->i_flags |= i_has_xattr_dir;

        err = xattr_readdir(dir->d_inode, reiserfs_listxattr_filler, &buf);
        if (err)
                goto out_dir;

        if (buf.r_pos > buf.r_size && buffer != NULL)
                err = -ERANGE;
        else
                err = buf.r_pos;

      out_dir:
        dput(dir);

      out:
        reiserfs_read_unlock_xattr_i(dentry->d_inode);
        return err;
}

/* This is the implementation for the xattr plugin infrastructure */
static LIST_HEAD(xattr_handlers);
static DEFINE_RWLOCK(handler_lock);

static struct reiserfs_xattr_handler *find_xattr_handler_prefix(const char
                                                                *prefix)
{
        struct reiserfs_xattr_handler *xah = NULL;
        struct list_head *p;

        read_lock(&handler_lock);
        list_for_each(p, &xattr_handlers) {
                xah = list_entry(p, struct reiserfs_xattr_handler, handlers);
                if (strncmp(xah->prefix, prefix, strlen(xah->prefix)) == 0)
                        break;
                xah = NULL;
        }

        read_unlock(&handler_lock);
        return xah;
}

static void __unregister_handlers(void)
{
        struct reiserfs_xattr_handler *xah;
        struct list_head *p, *tmp;

        list_for_each_safe(p, tmp, &xattr_handlers) {
                xah = list_entry(p, struct reiserfs_xattr_handler, handlers);
                if (xah->exit)
                        xah->exit();

                list_del_init(p);
        }
        INIT_LIST_HEAD(&xattr_handlers);
}

int __init reiserfs_xattr_register_handlers(void)
{
        int err = 0;
        struct reiserfs_xattr_handler *xah;
        struct list_head *p;

        write_lock(&handler_lock);

        /* If we're already initialized, nothing to do */
        if (!list_empty(&xattr_handlers)) {
                write_unlock(&handler_lock);
                return 0;
        }

        /* Add the handlers */
        list_add_tail(&user_handler.handlers, &xattr_handlers);
        list_add_tail(&trusted_handler.handlers, &xattr_handlers);
#ifdef CONFIG_REISERFS_FS_SECURITY
        list_add_tail(&security_handler.handlers, &xattr_handlers);
#endif
#ifdef CONFIG_REISERFS_FS_POSIX_ACL
        list_add_tail(&posix_acl_access_handler.handlers, &xattr_handlers);
        list_add_tail(&posix_acl_default_handler.handlers, &xattr_handlers);
#endif

        /* Run initializers, if available */
        list_for_each(p, &xattr_handlers) {
                xah = list_entry(p, struct reiserfs_xattr_handler, handlers);
                if (xah->init) {
                        err = xah->init();
                        if (err) {
                                list_del_init(p);
                                break;
                        }
                }
        }

        /* Clean up other handlers, if any failed */
        if (err)
                __unregister_handlers();

        write_unlock(&handler_lock);
        return err;
}

void reiserfs_xattr_unregister_handlers(void)
{
        write_lock(&handler_lock);
        __unregister_handlers();
        write_unlock(&handler_lock);
}

/* This will catch lookups from the fs root to .reiserfs_priv */
static int
xattr_lookup_poison(struct dentry *dentry, struct qstr *q1, struct qstr *name)
{
        struct dentry *priv_root = REISERFS_SB(dentry->d_sb)->priv_root;
        if (name->len == priv_root->d_name.len &&
            name->hash == priv_root->d_name.hash &&
            !memcmp(name->name, priv_root->d_name.name, name->len)) {
                return -ENOENT;
        } else if (q1->len == name->len &&
                   !memcmp(q1->name, name->name, name->len))
                return 0;
        return 1;
}

static struct dentry_operations xattr_lookup_poison_ops = {
        .d_compare = xattr_lookup_poison,
};

/* We need to take a copy of the mount flags since things like
 * MS_RDONLY don't get set until *after* we're called.
 * mount_flags != mount_options */
int reiserfs_xattr_init(struct super_block *s, int mount_flags)
{
        int err = 0;

        /* We need generation numbers to ensure that the oid mapping is correct
         * v3.5 filesystems don't have them. */
        if (!old_format_only(s)) {
                set_bit(REISERFS_XATTRS, &(REISERFS_SB(s)->s_mount_opt));
        } else if (reiserfs_xattrs_optional(s)) {
                /* Old format filesystem, but optional xattrs have been enabled
                 * at mount time. Error out. */
                reiserfs_warning(s, "xattrs/ACLs not supported on pre v3.6 "
                                 "format filesystem. Failing mount.");
                err = -EOPNOTSUPP;
                goto error;
        } else {
                /* Old format filesystem, but no optional xattrs have been enabled. This
                 * means we silently disable xattrs on the filesystem. */
                clear_bit(REISERFS_XATTRS, &(REISERFS_SB(s)->s_mount_opt));
        }

        /* If we don't have the privroot located yet - go find it */
        if (reiserfs_xattrs(s) && !REISERFS_SB(s)->priv_root) {
                struct dentry *dentry;
                dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
                                        strlen(PRIVROOT_NAME));
                if (!IS_ERR(dentry)) {
                        if (!(mount_flags & MS_RDONLY) && !dentry->d_inode) {
                                struct inode *inode = dentry->d_parent->d_inode;
                                mutex_lock_nested(&inode->i_mutex,
                                                  I_MUTEX_XATTR);
                                err = inode->i_op->mkdir(inode, dentry, 0700);
                                mutex_unlock(&inode->i_mutex);
                                if (err) {
                                        dput(dentry);
                                        dentry = NULL;
                                }

                                if (dentry && dentry->d_inode)
                                        reiserfs_warning(s,
                                                         "Created %s on %s - reserved for "
                                                         "xattr storage.",
                                                         PRIVROOT_NAME,
                                                         reiserfs_bdevname
                                                         (inode->i_sb));
                        } else if (!dentry->d_inode) {
                                dput(dentry);
                                dentry = NULL;
                        }
                } else
                        err = PTR_ERR(dentry);

                if (!err && dentry) {
                        s->s_root->d_op = &xattr_lookup_poison_ops;
                        reiserfs_mark_inode_private(dentry->d_inode);
                        REISERFS_SB(s)->priv_root = dentry;
                } else if (!(mount_flags & MS_RDONLY)) {        /* xattrs are unavailable */
                        /* If we're read-only it just means that the dir hasn't been
                         * created. Not an error -- just no xattrs on the fs. We'll
                         * check again if we go read-write */
                        reiserfs_warning(s, "xattrs/ACLs enabled and couldn't "
                                         "find/create .reiserfs_priv. Failing mount.");
                        err = -EOPNOTSUPP;
                }
        }

      error:
        /* This is only nonzero if there was an error initializing the xattr
         * directory or if there is a condition where we don't support them. */
        if (err) {
                clear_bit(REISERFS_XATTRS, &(REISERFS_SB(s)->s_mount_opt));
                clear_bit(REISERFS_XATTRS_USER, &(REISERFS_SB(s)->s_mount_opt));
                clear_bit(REISERFS_POSIXACL, &(REISERFS_SB(s)->s_mount_opt));
        }

        /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */
        s->s_flags = s->s_flags & ~MS_POSIXACL;
        if (reiserfs_posixacl(s))
                s->s_flags |= MS_POSIXACL;

        return err;
}

static int reiserfs_check_acl(struct inode *inode, int mask)
{
        struct posix_acl *acl;
        int error = -EAGAIN; /* do regular unix permission checks by default */

        reiserfs_read_lock_xattr_i(inode);
        reiserfs_read_lock_xattrs(inode->i_sb);

        acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);

        reiserfs_read_unlock_xattrs(inode->i_sb);
        reiserfs_read_unlock_xattr_i(inode);

        if (acl) {
                if (!IS_ERR(acl)) {
                        error = posix_acl_permission(inode, acl, mask);
                        posix_acl_release(acl);
                } else if (PTR_ERR(acl) != -ENODATA)
                        error = PTR_ERR(acl);
        }

        return error;
}

int reiserfs_permission(struct inode *inode, int mask)
{
        /*
         * We don't do permission checks on the internal objects.
         * Permissions are determined by the "owning" object.
         */
        if (is_reiserfs_priv_object(inode))
                return 0;

        /*
         * Stat data v1 doesn't support ACLs.
         */
        if (get_inode_sd_version(inode) == STAT_DATA_V1)
                return generic_permission(inode, mask, NULL);
        else
                return generic_permission(inode, mask, reiserfs_check_acl);
}