reiserfs: simplify xattr internal file lookups/opens

The xattr file open/lookup code is needlessly complex.  We can use
vfs-level operations to perform the same work, and also simplify the
locking constraints.  The locking advantages will be exploited in future
patches.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index f9bcdd5750f7be288ae7cd21fba2224a77c30f61..57920a4df7a4d616fd2fe28912c1e1ff394e0668 100644 (file)
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -44,100 +44,123 @@
 #include <net/checksum.h>
 #include <linux/smp_lock.h>
 #include <linux/stat.h>
+#include <linux/quotaops.h>
 
-#define FL_READONLY 128
-#define FL_DIR_SEM_HELD 256
 #define PRIVROOT_NAME ".reiserfs_priv"
 #define XAROOT_NAME   "xattrs"
 
-/* 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)
+/* Helpers for inode ops. We do this so that we don't have all the VFS
+ * overhead and also for proper i_mutex annotation.
+ * dir->i_mutex must be held for all of them. */
+static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
 {
-       struct dentry *privroot = dget(REISERFS_SB(sb)->priv_root);
-       struct dentry *xaroot;
+       BUG_ON(!mutex_is_locked(&dir->i_mutex));
+       DQUOT_INIT(dir);
+       return dir->i_op->create(dir, dentry, mode, NULL);
+}
 
-       /* This needs to be created at mount-time */
-       if (!privroot)
-               return ERR_PTR(-ENODATA);
+static int xattr_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+       BUG_ON(!mutex_is_locked(&dir->i_mutex));
+       DQUOT_INIT(dir);
+       return dir->i_op->mkdir(dir, dentry, mode);
+}
 
-       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;
-       }
+/* We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
+ * mutation ops aren't called during rename or splace, which are the
+ * only other users of I_MUTEX_CHILD. It violates the ordering, but that's
+ * better than allocating another subclass just for this code. */
+static int xattr_unlink(struct inode *dir, struct dentry *dentry)
+{
+       int error;
+       BUG_ON(!mutex_is_locked(&dir->i_mutex));
+       DQUOT_INIT(dir);
 
-       xaroot = lookup_one_len(XAROOT_NAME, privroot, strlen(XAROOT_NAME));
-       if (IS_ERR(xaroot)) {
-               goto out;
-       } else if (!xaroot->d_inode) {
+       mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+       error = dir->i_op->unlink(dir, dentry);
+       mutex_unlock(&dentry->d_inode->i_mutex);
+
+       if (!error)
+               d_delete(dentry);
+       return error;
+}
+
+static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
+{
+       int error;
+       BUG_ON(!mutex_is_locked(&dir->i_mutex));
+       DQUOT_INIT(dir);
+
+       mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+       dentry_unhash(dentry);
+       error = dir->i_op->rmdir(dir, dentry);
+       if (!error)
+               dentry->d_inode->i_flags |= S_DEAD;
+       mutex_unlock(&dentry->d_inode->i_mutex);
+       if (!error)
+               d_delete(dentry);
+       dput(dentry);
+
+       return error;
+}
+
+
+#define xattr_may_create(flags)        (!flags || flags & XATTR_CREATE)
+
+/* Returns and possibly creates the xattr dir. */
+static struct dentry *lookup_or_create_dir(struct dentry *parent,
+                                           const char *name, int flags)
+{
+       struct dentry *dentry;
+       BUG_ON(!parent);
+
+       dentry = lookup_one_len(name, parent, strlen(name));
+       if (IS_ERR(dentry))
+               return dentry;
+       else if (!dentry->d_inode) {
                int err = -ENODATA;
-               if (flags == 0 || flags & XATTR_CREATE)
-                       err = privroot->d_inode->i_op->mkdir(privroot->d_inode,
-                                                            xaroot, 0700);
+
+               if (xattr_may_create(flags)) {
+                       mutex_lock_nested(&parent->d_inode->i_mutex,
+                                         I_MUTEX_XATTR);
+                       err = xattr_mkdir(parent->d_inode, dentry, 0700);
+                       mutex_unlock(&parent->d_inode->i_mutex);
+               }
+
                if (err) {
-                       dput(xaroot);
-                       xaroot = ERR_PTR(err);
-                       goto out;
+                       dput(dentry);
+                       dentry = ERR_PTR(err);
                }
        }
-       REISERFS_SB(sb)->xattr_root = dget(xaroot);
 
-      out:
-       mutex_unlock(&privroot->d_inode->i_mutex);
-       dput(privroot);
-       return xaroot;
+       return dentry;
+}
+
+static struct dentry *open_xa_root(struct super_block *sb, int flags)
+{
+       struct dentry *privroot = REISERFS_SB(sb)->priv_root;
+       if (!privroot)
+               return ERR_PTR(-ENODATA);
+       return lookup_or_create_dir(privroot, XAROOT_NAME, flags);
 }
 
-/* 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);
+       xaroot = open_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);
-               }
-       }
 
+       xadir = lookup_or_create_dir(xaroot, namebuf, flags);
        dput(xaroot);
        return xadir;
+
 }
 
 /*
@@ -302,13 +325,11 @@ 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;
 }
 
@@ -345,9 +366,7 @@ __reiserfs_xattr_del(struct dentry *xadir, const char *name, int namelen)
                return -EIO;
        }
 
-       err = dir->i_op->unlink(dir, dentry);
-       if (!err)
-               d_delete(dentry);
+       err = xattr_unlink(dir, dentry);
 
 out_file:
        dput(dentry);
@@ -381,7 +400,7 @@ int reiserfs_delete_xattrs(struct inode *inode)
                return 0;
 
        reiserfs_read_lock_xattrs(inode->i_sb);
-       dir = open_xa_dir(inode, FL_READONLY);
+       dir = open_xa_dir(inode, XATTR_REPLACE);
        reiserfs_read_unlock_xattrs(inode->i_sb);
        if (IS_ERR(dir)) {
                err = PTR_ERR(dir);
@@ -391,25 +410,25 @@ int reiserfs_delete_xattrs(struct inode *inode)
                return 0;
        }
 
-       lock_kernel();
+       mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
        err = xattr_readdir(dir->d_inode, reiserfs_delete_xattrs_filler, dir);
-       if (err) {
-               unlock_kernel();
+       mutex_unlock(&dir->d_inode->i_mutex);
+       if (err)
                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);
+               root = open_xa_root(inode->i_sb, XATTR_REPLACE);
                reiserfs_write_lock_xattrs(inode->i_sb);
-               err = vfs_rmdir(root->d_inode, dir);
+               mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_XATTR);
+               err = xattr_rmdir(root->d_inode, dir);
+               mutex_unlock(&root->d_inode->i_mutex);
                reiserfs_write_unlock_xattrs(inode->i_sb);
                dput(root);
        } else {
                reiserfs_warning(inode->i_sb, "jdm-20006",
                                 "Couldn't remove all entries in directory");
        }
-       unlock_kernel();
 
 out_dir:
        dput(dir);
@@ -445,8 +464,11 @@ reiserfs_chown_xattrs_filler(void *buf, const char *name, int namelen,
                return -ENODATA;
        }
 
-       if (!S_ISDIR(xafile->d_inode->i_mode))
+       if (!S_ISDIR(xafile->d_inode->i_mode)) {
+               mutex_lock_nested(&xafile->d_inode->i_mutex, I_MUTEX_CHILD);
                err = notify_change(xafile, attrs);
+               mutex_unlock(&xafile->d_inode->i_mutex);
+       }
        dput(xafile);
 
        return err;
@@ -464,38 +486,31 @@ int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
                return 0;
 
        reiserfs_read_lock_xattrs(inode->i_sb);
-       dir = open_xa_dir(inode, FL_READONLY);
+       dir = open_xa_dir(inode, XATTR_REPLACE);
        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();
+       } else if (!dir->d_inode)
+               goto out_dir;
 
        attrs->ia_valid &= (ATTR_UID | ATTR_GID | ATTR_CTIME);
        buf.xadir = dir;
        buf.attrs = attrs;
        buf.inode = inode;
 
+       mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
        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();
+       if (!err)
+               err = notify_change(dir, attrs);
+       mutex_unlock(&dir->d_inode->i_mutex);
 
+       attrs->ia_valid = ia_valid;
 out_dir:
        dput(dir);
-
 out:
-       attrs->ia_valid = ia_valid;
        return err;
 }
 
@@ -513,47 +528,35 @@ static struct dentry *get_xa_file_dentry(const struct inode *inode,
        int err = 0;
 
        xadir = open_xa_dir(inode, flags);
-       if (IS_ERR(xadir)) {
+       if (IS_ERR(xadir))
                return ERR_CAST(xadir);
-       } else if (xadir && !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);
+               err = PTR_ERR(xafile);
+               goto out;
        }
 
-       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 (xafile->d_inode && (flags & XATTR_CREATE))
+               err = -EEXIST;
 
-               if (err) {
-                       dput(xafile);
-                       goto out;
+       if (!xafile->d_inode) {
+               err = -ENODATA;
+               if (xattr_may_create(flags)) {
+                       mutex_lock_nested(&xadir->d_inode->i_mutex,
+                                         I_MUTEX_XATTR);
+                       err = xattr_create(xadir->d_inode, xafile,
+                                             0700|S_IFREG);
+                       mutex_unlock(&xadir->d_inode->i_mutex);
                }
        }
 
+       if (err)
+               dput(xafile);
 out:
        dput(xadir);
        if (err)
-               xafile = ERR_PTR(err);
-       else if (!xafile->d_inode) {
-               dput(xafile);
-               xafile = ERR_PTR(-ENODATA);
-       }
+               return ERR_PTR(err);
        return xafile;
 }
 
@@ -633,6 +636,7 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
        newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
        mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
        err = notify_change(dentry, &newattrs);
+       mutex_unlock(&dentry->d_inode->i_mutex);
        if (err)
                goto out_filp;
 
@@ -692,7 +696,6 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
        }
 
       out_filp:
-       mutex_unlock(&dentry->d_inode->i_mutex);
        dput(dentry);
 
       out:
@@ -722,7 +725,7 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
        if (get_inode_sd_version(inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       dentry = get_xa_file_dentry(inode, name, FL_READONLY);
+       dentry = get_xa_file_dentry(inode, name, XATTR_REPLACE);
        if (IS_ERR(dentry)) {
                err = PTR_ERR(dentry);
                goto out;
@@ -806,13 +809,15 @@ int reiserfs_xattr_del(struct inode *inode, const char *name)
        struct dentry *dir;
        int err;
 
-       dir = open_xa_dir(inode, FL_READONLY);
+       dir = open_xa_dir(inode, XATTR_REPLACE);
        if (IS_ERR(dir)) {
                err = PTR_ERR(dir);
                goto out;
        }
 
+       mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
        err = __reiserfs_xattr_del(dir, name, strlen(name));
+       mutex_unlock(&dir->d_inode->i_mutex);
        dput(dir);
 
        if (!err) {
@@ -826,6 +831,7 @@ int reiserfs_xattr_del(struct inode *inode, const char *name)
 
 /* Actual operations that are exported to VFS-land */
 
+static struct reiserfs_xattr_handler *find_xattr_handler_prefix(const char *);
 /*
  * Inode operation getxattr()
  * Preliminary locking: we down dentry->d_inode->i_mutex
@@ -978,7 +984,7 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
 
        reiserfs_read_lock_xattr_i(dentry->d_inode);
        reiserfs_read_lock_xattrs(dentry->d_sb);
-       dir = open_xa_dir(dentry->d_inode, FL_READONLY);
+       dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
        reiserfs_read_unlock_xattrs(dentry->d_sb);
        if (IS_ERR(dir)) {
                err = PTR_ERR(dir);
@@ -994,7 +1000,9 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
 
        REISERFS_I(dentry->d_inode)->i_flags |= i_has_xattr_dir;
 
+       mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
        err = xattr_readdir(dir->d_inode, reiserfs_listxattr_filler, &buf);
+       mutex_unlock(&dir->d_inode->i_mutex);
        if (err)
                goto out_dir;
 
@@ -1146,7 +1154,7 @@ static int create_privroot(struct dentry *dentry)
        int err;
        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);
+       err = xattr_mkdir(inode, dentry, 0700);
        mutex_unlock(&inode->i_mutex);
        if (err) {
                dput(dentry);