f2fs: avoid race in between read xattr & write xattr

Thread A: Thread B: -f2fs_getxattr -lookup_all_xattrs -xnid = F2FS_I(inode)->i_xattr_nid; -f2fs_setxattr -__f2fs_setxattr -write_all_xattrs -truncate_xattr_node ... ... -write_checkpoint ... ... -alloc_nid <- nid reuse -get_node_page -f2fs_bug_on <- nid != node_footer->nid It's need a rw_sem to avoid the race Signed-off-by: Yunlei He <[email protected]> Reviewed-by: Chao Yu <[email protected]> Signed-off-by: Jaegeuk Kim <[email protected]>
Kwiboo · Sep 8, 2017 · 27161f1 · 27161f1
1 parent 13ba41e
commit 27161f1
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diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
@@ -589,6 +589,7 @@ struct f2fs_inode_info {
 	struct extent_tree *extent_tree;	/* cached extent_tree entry */
 	struct rw_semaphore dio_rwsem[2];/* avoid racing between dio and gc */
 	struct rw_semaphore i_mmap_sem;
+	struct rw_semaphore i_xattr_sem; /* avoid racing between reading and changing EAs */
 
 	int i_extra_isize;		/* size of extra space located in i_addr */
 	kprojid_t i_projid;		/* id for project quota */

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
@@ -630,6 +630,7 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 	init_rwsem(&fi->dio_rwsem[READ]);
 	init_rwsem(&fi->dio_rwsem[WRITE]);
 	init_rwsem(&fi->i_mmap_sem);
+	init_rwsem(&fi->i_xattr_sem);
 
 #ifdef CONFIG_QUOTA
 	memset(&fi->i_dquot, 0, sizeof(fi->i_dquot));

diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
@@ -473,8 +473,10 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
 	if (len > F2FS_NAME_LEN)
 		return -ERANGE;
 
+	down_read(&F2FS_I(inode)->i_xattr_sem);
 	error = lookup_all_xattrs(inode, ipage, index, len, name,
 				&entry, &base_addr);
+	up_read(&F2FS_I(inode)->i_xattr_sem);
 	if (error)
 		return error;
 
@@ -503,7 +505,9 @@ ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 	int error = 0;
 	size_t rest = buffer_size;
 
+	down_read(&F2FS_I(inode)->i_xattr_sem);
 	error = read_all_xattrs(inode, NULL, &base_addr);
+	up_read(&F2FS_I(inode)->i_xattr_sem);
 	if (error)
 		return error;
 
@@ -686,7 +690,9 @@ int f2fs_setxattr(struct inode *inode, int index, const char *name,
 	f2fs_lock_op(sbi);
 	/* protect xattr_ver */
 	down_write(&F2FS_I(inode)->i_sem);
+	down_write(&F2FS_I(inode)->i_xattr_sem);
 	err = __f2fs_setxattr(inode, index, name, value, size, ipage, flags);
+	up_write(&F2FS_I(inode)->i_xattr_sem);
 	up_write(&F2FS_I(inode)->i_sem);
 	f2fs_unlock_op(sbi);