reiserfs: make per-inode xattr locking more fine grained

The per-inode locking can be made more fine-grained to surround just the
interaction with the filesystem itself.  This really only applies to
protecting reads during a write, since concurrent writes are barred with
inode->i_mutex at the vfs level.

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 62c9882..ccb8e4d 100644 (file)
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -29,10 +29,8 @@
  * to the inode so that unnecessary lookups are avoided.
  *
  * Locking works like so:
- * The xattr root (/.reiserfs_priv/xattrs) is protected by its i_mutex.
- * The xattr dir (/.reiserfs_priv/xattrs/<oid>.<gen>) is protected by
- * inode->xattr_sem.
- * The xattrs themselves are likewise protected by the xattr_sem.
+ * Directory components (xattr root, xattr dir) are protectd by their i_mutex.
+ * The xattrs themselves are protected by the xattr_sem.
  */
 
 #include <linux/reiserfs_fs.h>
@@ -55,6 +53,8 @@
 #define PRIVROOT_NAME ".reiserfs_priv"
 #define XAROOT_NAME   "xattrs"
 
+static struct reiserfs_xattr_handler *find_xattr_handler_prefix(const char *);
+
 /* 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. */
@@ -339,12 +339,14 @@ int xattr_readdir(struct inode *inode, filldir_t filler, void *buf)
        return res;
 }
 
+/* expects xadir->d_inode->i_mutex to be locked */
 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;
+       struct reiserfs_xattr_handler *xah;
 
        dentry = lookup_one_len(name, xadir, namelen);
        if (IS_ERR(dentry)) {
@@ -372,6 +374,14 @@ __reiserfs_xattr_del(struct dentry *xadir, const char *name, int namelen)
                return -EIO;
        }
 
+       /* Deletion pre-operation */
+       xah = find_xattr_handler_prefix(name);
+       if (xah && xah->del) {
+               err = xah->del(dentry->d_inode, name);
+               if (err)
+                       goto out;
+       }
+
        err = xattr_unlink(dir, dentry);
 
 out_file:
@@ -398,7 +408,7 @@ reiserfs_delete_xattrs_filler(void *buf, const char *name, int namelen,
 /* This is called w/ inode->i_mutex downed */
 int reiserfs_delete_xattrs(struct inode *inode)
 {
-       int err = 0;
+       int err = -ENODATA;
        struct dentry *dir, *root;
        struct reiserfs_transaction_handle th;
        int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
@@ -414,14 +424,19 @@ int reiserfs_delete_xattrs(struct inode *inode)
                goto out;
        } else if (!dir->d_inode) {
                dput(dir);
-               return 0;
+               goto out;
        }
 
        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
        err = xattr_readdir(dir->d_inode, reiserfs_delete_xattrs_filler, dir);
        mutex_unlock(&dir->d_inode->i_mutex);
-       if (err)
-               goto out_dir;
+       if (err) {
+               dput(dir);
+               goto out;
+       }
+
+       root = dget(dir->d_parent);
+       dput(dir);
 
        /* We start a transaction here to avoid a ABBA situation
         * between the xattr root's i_mutex and the journal lock.
@@ -435,19 +450,14 @@ int reiserfs_delete_xattrs(struct inode *inode)
        err = journal_begin(&th, inode->i_sb, blocks);
        if (!err) {
                int jerror;
-               root = dget(dir->d_parent);
                mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_XATTR);
                err = xattr_rmdir(root->d_inode, dir);
                jerror = journal_end(&th, inode->i_sb, blocks);
                mutex_unlock(&root->d_inode->i_mutex);
-               dput(root);
-
                err = jerror ?: err;
        }
 
-out_dir:
-       dput(dir);
-
+       dput(root);
 out:
        if (!err)
                REISERFS_I(inode)->i_flags =
@@ -484,7 +494,7 @@ reiserfs_chown_xattrs_filler(void *buf, const char *name, int namelen,
 
        if (!S_ISDIR(xafile->d_inode->i_mode)) {
                mutex_lock_nested(&xafile->d_inode->i_mutex, I_MUTEX_CHILD);
-               err = notify_change(xafile, attrs);
+               err = reiserfs_setattr(xafile, attrs);
                mutex_unlock(&xafile->d_inode->i_mutex);
        }
        dput(xafile);
@@ -520,13 +530,16 @@ int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
        err = xattr_readdir(dir->d_inode, reiserfs_chown_xattrs_filler, &buf);
 
        if (!err)
-               err = notify_change(dir, attrs);
+               err = reiserfs_setattr(dir, attrs);
        mutex_unlock(&dir->d_inode->i_mutex);
 
        attrs->ia_valid = ia_valid;
 out_dir:
        dput(dir);
 out:
+       if (err)
+               reiserfs_warning(inode->i_sb, "jdm-20007",
+                                "Couldn't chown all xattrs (%d)\n", err);
        return err;
 }
 
@@ -635,9 +648,8 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
        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);
+       if (!buffer)
+               return reiserfs_xattr_del(inode, name);
 
        dentry = get_xa_file_dentry(inode, name, flags);
        if (IS_ERR(dentry)) {
@@ -645,13 +657,19 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
                goto out;
        }
 
+       down_write(&REISERFS_I(inode)->i_xattr_sem);
+
+       xahash = xattr_hash(buffer, buffer_size);
        REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 
        /* Resize it so we're ok to write there */
        newattrs.ia_size = buffer_size;
+       newattrs.ia_ctime = current_fs_time(inode->i_sb);
        newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
        mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
-       err = notify_change(dentry, &newattrs);
+       down_write(&dentry->d_inode->i_alloc_sem);
+       err = reiserfs_setattr(dentry, &newattrs);
+       up_write(&dentry->d_inode->i_alloc_sem);
        mutex_unlock(&dentry->d_inode->i_mutex);
        if (err)
                goto out_filp;
@@ -712,6 +730,7 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
        }
 
       out_filp:
+       up_write(&REISERFS_I(inode)->i_xattr_sem);
        dput(dentry);
 
       out:
@@ -747,10 +766,7 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
                goto out;
        }
 
-       /* protect against concurrent access. xattrs are backed by
-        * regular files, but they're not regular files. The updates
-        * must be atomic from the perspective of the user. */
-       mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
+       down_read(&REISERFS_I(inode)->i_xattr_sem);
 
        isize = i_size_read(dentry->d_inode);
        REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
@@ -758,12 +774,12 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
        /* Just return the size needed */
        if (buffer == NULL) {
                err = isize - sizeof(struct reiserfs_xattr_header);
-               goto out_dput;
+               goto out_unlock;
        }
 
        if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
                err = -ERANGE;
-               goto out_dput;
+               goto out_unlock;
        }
 
        while (file_pos < isize) {
@@ -778,7 +794,7 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
                page = reiserfs_get_page(dentry->d_inode, file_pos);
                if (IS_ERR(page)) {
                        err = PTR_ERR(page);
-                       goto out_dput;
+                       goto out_unlock;
                }
 
                lock_page(page);
@@ -797,7 +813,7 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
                                                 "associated with %k", name,
                                                 INODE_PKEY(inode));
                                err = -EIO;
-                               goto out_dput;
+                               goto out_unlock;
                        }
                        hash = le32_to_cpu(rxh->h_hash);
                }
@@ -818,8 +834,8 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
                err = -EIO;
        }
 
-out_dput:
-       mutex_unlock(&dentry->d_inode->i_mutex);
+out_unlock:
+       up_read(&REISERFS_I(inode)->i_xattr_sem);
        dput(dentry);
 
 out:
@@ -852,8 +868,6 @@ 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()
  */
@@ -868,9 +882,7 @@ reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer,
            get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       reiserfs_read_lock_xattr_i(dentry->d_inode);
        err = xah->get(dentry->d_inode, name, buffer, size);
-       reiserfs_read_unlock_xattr_i(dentry->d_inode);
        return err;
 }
 
@@ -890,9 +902,7 @@ reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value,
            get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       reiserfs_write_lock_xattr_i(dentry->d_inode);
        err = xah->set(dentry->d_inode, name, value, size, flags);
-       reiserfs_write_unlock_xattr_i(dentry->d_inode);
        return err;
 }
 
@@ -910,21 +920,11 @@ int reiserfs_removexattr(struct dentry *dentry, const char *name)
            get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       reiserfs_write_lock_xattr_i(dentry->d_inode);
-       /* 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_write_unlock_xattr_i(dentry->d_inode);
        return err;
 }
 
@@ -986,7 +986,6 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
            get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       reiserfs_read_lock_xattr_i(dentry->d_inode);
        dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
        if (IS_ERR(dir)) {
                err = PTR_ERR(dir);
@@ -1005,19 +1004,16 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
        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;
 
-       if (buf.r_pos > buf.r_size && buffer != NULL)
-               err = -ERANGE;
-       else
-               err = buf.r_pos;
+       if (!err) {
+               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);
+out:
        return err;
 }
 
@@ -1115,12 +1111,8 @@ 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);
-
        acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
 
-       reiserfs_read_unlock_xattr_i(inode);
-
        if (acl) {
                if (!IS_ERR(acl)) {
                        error = posix_acl_permission(inode, acl, mask);

diff --git a/fs/reiserfs/xattr_acl.c b/fs/reiserfs/xattr_acl.c
index d63b2c5..d3ce6ee 100644 (file)
--- a/fs/reiserfs/xattr_acl.c
+++ b/fs/reiserfs/xattr_acl.c
@@ -418,9 +418,7 @@ int reiserfs_cache_default_acl(struct inode *inode)
        int ret = 0;
        if (reiserfs_posixacl(inode->i_sb) && !IS_PRIVATE(inode)) {
                struct posix_acl *acl;
-               reiserfs_read_lock_xattr_i(inode);
                acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
-               reiserfs_read_unlock_xattr_i(inode);
                ret = (acl && !IS_ERR(acl));
                if (ret)
                        posix_acl_release(acl);
@@ -452,11 +450,8 @@ int reiserfs_acl_chmod(struct inode *inode)
        if (!clone)
                return -ENOMEM;
        error = posix_acl_chmod_masq(clone, inode->i_mode);
-       if (!error) {
-               reiserfs_write_lock_xattr_i(inode);
+       if (!error)
                error = reiserfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
-               reiserfs_write_unlock_xattr_i(inode);
-       }
        posix_acl_release(clone);
        return error;
 }

diff --git a/include/linux/reiserfs_fs_i.h b/include/linux/reiserfs_fs_i.h
index 201dd91..76360b3 100644 (file)
--- a/include/linux/reiserfs_fs_i.h
+++ b/include/linux/reiserfs_fs_i.h
@@ -59,7 +59,7 @@ struct reiserfs_inode_info {
        struct posix_acl *i_acl_default;
 #endif
 #ifdef CONFIG_REISERFS_FS_XATTR
-       struct rw_semaphore xattr_sem;
+       struct rw_semaphore i_xattr_sem;
 #endif
        struct inode vfs_inode;
 };

diff --git a/include/linux/reiserfs_xattr.h b/include/linux/reiserfs_xattr.h
index 65c16fa..3bd154f 100644 (file)
--- a/include/linux/reiserfs_xattr.h
+++ b/include/linux/reiserfs_xattr.h
@@ -67,24 +67,6 @@ extern struct reiserfs_xattr_handler user_handler;
 extern struct reiserfs_xattr_handler trusted_handler;
 extern struct reiserfs_xattr_handler security_handler;
 
-static inline void reiserfs_write_lock_xattr_i(struct inode *inode)
-{
-       down_write(&REISERFS_I(inode)->i_xattr_sem);
-}
-static inline void reiserfs_write_unlock_xattr_i(struct inode *inode)
-{
-       up_write(&REISERFS_I(inode)->i_xattr_sem);
-}
-static inline void reiserfs_read_lock_xattr_i(struct inode *inode)
-{
-       down_read(&REISERFS_I(inode)->i_xattr_sem);
-}
-
-static inline void reiserfs_read_unlock_xattr_i(struct inode *inode)
-{
-       up_read(&REISERFS_I(inode)->i_xattr_sem);
-}
-
 static inline void reiserfs_init_xattr_rwsem(struct inode *inode)
 {
        init_rwsem(&REISERFS_I(inode)->i_xattr_sem);
@@ -96,10 +78,6 @@ static inline void reiserfs_init_xattr_rwsem(struct inode *inode)
 #define reiserfs_setxattr NULL
 #define reiserfs_listxattr NULL
 #define reiserfs_removexattr NULL
-#define reiserfs_write_lock_xattrs(sb) do {;} while(0)
-#define reiserfs_write_unlock_xattrs(sb) do {;} while(0)
-#define reiserfs_read_lock_xattrs(sb)
-#define reiserfs_read_unlock_xattrs(sb)
 
 #define reiserfs_permission NULL