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f2fs: avoid race in between read xattr & write xattr

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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 <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Yunlei He
2017-09-07 10:40:54 +08:00
committed by Jaegeuk Kim
parent 13ba41e346
commit 27161f13e3
3 changed files with 8 additions and 0 deletions
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6
fs/f2fs/xattr.c
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@@ -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);