reiserfs: journaled xattrs

Deadlocks are possible in the xattr code between the journal lock and the
xattr sems.

This patch implements journalling for xattr operations. The benefit is
twofold:
 * It gets rid of the deadlock possibility by always ensuring that xattr
   write operations are initiated inside a transaction.
 * It corrects the problem where xattr backing files aren't considered any
   differently than normal files, despite the fact they are metadata.

I discussed the added journal load with Chris Mason, and we decided that
since xattrs (versus other journal activity) is fairly rare, the introduction
of larger transactions to support journaled xattrs wouldn't be too big a deal.

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

1 files changed, 38 insertions, 2 deletions

diff --git a/include/linux/reiserfs_xattr.h b/include/linux/reiserfs_xattr.h
index 958fcac..20eca09 100644
--- a/include/linux/reiserfs_xattr.h
+++ b/include/linux/reiserfs_xattr.h
@@ -46,14 +46,50 @@ int reiserfs_removexattr(struct dentry *dentry, const char *name);
 int reiserfs_permission(struct inode *inode, int mask);
 
 int reiserfs_xattr_get(struct inode *, const char *, void *, size_t);
-int __reiserfs_xattr_set(struct inode *, const char *, const void *,
-			 size_t, int);
 int reiserfs_xattr_set(struct inode *, const char *, const void *, size_t, int);
+int reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *,
+			      struct inode *, const char *, const void *,
+			      size_t, int);
 
 extern struct xattr_handler reiserfs_xattr_user_handler;
 extern struct xattr_handler reiserfs_xattr_trusted_handler;
 extern struct xattr_handler reiserfs_xattr_security_handler;
 
+#define xattr_size(size) ((size) + sizeof(struct reiserfs_xattr_header))
+static inline loff_t reiserfs_xattr_nblocks(struct inode *inode, loff_t size)
+{
+	loff_t ret = 0;
+	if (reiserfs_file_data_log(inode)) {
+		ret = _ROUND_UP(xattr_size(size), inode->i_sb->s_blocksize);
+		ret >>= inode->i_sb->s_blocksize_bits;
+	}
+	return ret;
+}
+
+/* We may have to create up to 3 objects: xattr root, xattr dir, xattr file.
+ * Let's try to be smart about it.
+ * xattr root: We cache it. If it's not cached, we may need to create it.
+ * xattr dir: If anything has been loaded for this inode, we can set a flag
+ *            saying so.
+ * xattr file: Since we don't cache xattrs, we can't tell. We always include
+ *             blocks for it.
+ *
+ * However, since root and dir can be created between calls - YOU MUST SAVE
+ * THIS VALUE.
+ */
+static inline size_t reiserfs_xattr_jcreate_nblocks(struct inode *inode)
+{
+	size_t nblocks = JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
+
+	if ((REISERFS_I(inode)->i_flags & i_has_xattr_dir) == 0) {
+		nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
+		if (REISERFS_SB(inode->i_sb)->xattr_root == NULL)
+			nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
+	}
+
+	return nblocks;
+}
+
 static inline void reiserfs_init_xattr_rwsem(struct inode *inode)
 {
 	init_rwsem(&REISERFS_I(inode)->i_xattr_sem);