[PATCH] xattr locking

This is a patch from Andreas Gruenbacher (the ext2/ext3 EA patch
maintainer) which converts the extended attribute VFS code from
using the BKL to instead use the inode semaphore; please apply.

Documentation/filesystems/Locking

@@ -69,10 +69,10 @@ setattr:	no	yes
 permission:	yes	no
 getattr:				(see below)
 revalidate:	no			(see below)
-setxattr:	yes	no
-getxattr:	yes	no
-listxattr:	yes	no
-removexattr:	yes	no
+setxattr:	no	yes
+getxattr:	no	yes
+listxattr:	no	yes
+removexattr:	no	yes
 	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_sem on
 victim.
 	cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem.

fs/xattr.c

@@ -84,9 +84,9 @@ setxattr(struct dentry *d, char *name, void *value, size_t size, int flags)
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
-		lock_kernel();
+		down(&d->d_inode->i_sem);
 		error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
-		unlock_kernel();
+		up(&d->d_inode->i_sem);
 	}
 
 	xattr_free(kvalue, size);
@@ -157,9 +157,9 @@ getxattr(struct dentry *d, char *name, void *value, size_t size)
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
-		lock_kernel();
+		down(&d->d_inode->i_sem);
 		error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
-		unlock_kernel();
+		up(&d->d_inode->i_sem);
 	}
 
 	if (kvalue && error > 0)
@@ -226,9 +226,9 @@ listxattr(struct dentry *d, char *list, size_t size)
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
-		lock_kernel();
+		down(&d->d_inode->i_sem);
 		error = d->d_inode->i_op->listxattr(d, klist, size);
-		unlock_kernel();
+		up(&d->d_inode->i_sem);
 	}
 
 	if (klist && error > 0)
@@ -297,9 +297,9 @@ removexattr(struct dentry *d, char *name)
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
-		lock_kernel();
+		down(&d->d_inode->i_sem);
 		error = d->d_inode->i_op->removexattr(d, kname);
-		unlock_kernel();
+		up(&d->d_inode->i_sem);
 	}
 	return error;
 }