Commit 16c8d569 authored by piaojun's avatar piaojun Committed by Linus Torvalds
Browse files

ocfs2/acl: use 'ip_xattr_sem' to protect getting extended attribute 

The race between *set_acl and *get_acl will cause getting incomplete
xattr data as below:

  processA                                    processB

  ocfs2_set_acl
    ocfs2_xattr_set
      __ocfs2_xattr_set_handle

                                              ocfs2_get_acl_nolock
                                                ocfs2_xattr_get_nolock:

processB may get incomplete xattr data if processA hasn't set_acl done.

So we should use 'ip_xattr_sem' to protect getting extended attribute in
ocfs2_get_acl_nolock(), as other processes could be changing it
concurrently.

Link: http://lkml.kernel.org/r/5A5DDCFF.7030001@huawei.com


Signed-off-by: default avatarJun Piao <piaojun@huawei.com>
Reviewed-by: default avatarAlex Chen <alex.chen@huawei.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d22aa615

fs/ocfs2/acl.c

+6 −0
Original line number Diff line number Diff line
@@ -311,7 +311,9 @@ struct posix_acl *ocfs2_iop_get_acl(struct inode *inode, int type) 
	if (had_lock < 0)

		return ERR_PTR(had_lock);



	down_read(&OCFS2_I(inode)->ip_xattr_sem);

	acl = ocfs2_get_acl_nolock(inode, type, di_bh);

	up_read(&OCFS2_I(inode)->ip_xattr_sem);



	ocfs2_inode_unlock_tracker(inode, 0, &oh, had_lock);

	brelse(di_bh);
@@ -330,7 +332,9 @@ int ocfs2_acl_chmod(struct inode *inode, struct buffer_head *bh) 
	if (!(osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL))

		return 0;



	down_read(&OCFS2_I(inode)->ip_xattr_sem);

	acl = ocfs2_get_acl_nolock(inode, ACL_TYPE_ACCESS, bh);

	up_read(&OCFS2_I(inode)->ip_xattr_sem);

	if (IS_ERR(acl) || !acl)

		return PTR_ERR(acl);

	ret = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
@@ -361,8 +365,10 @@ int ocfs2_init_acl(handle_t *handle, 


	if (!S_ISLNK(inode->i_mode)) {

		if (osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL) {

			down_read(&OCFS2_I(dir)->ip_xattr_sem);

			acl = ocfs2_get_acl_nolock(dir, ACL_TYPE_DEFAULT,

						   dir_bh);

			up_read(&OCFS2_I(dir)->ip_xattr_sem);

			if (IS_ERR(acl))

				return PTR_ERR(acl);

		}

fs/ocfs2/xattr.c

+2 −0
Original line number Diff line number Diff line
@@ -638,9 +638,11 @@ int ocfs2_calc_xattr_init(struct inode *dir, 
						     si->value_len);



	if (osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL) {

		down_read(&OCFS2_I(dir)->ip_xattr_sem);

		acl_len = ocfs2_xattr_get_nolock(dir, dir_bh,

					OCFS2_XATTR_INDEX_POSIX_ACL_DEFAULT,

					"", NULL, 0);

		up_read(&OCFS2_I(dir)->ip_xattr_sem);

		if (acl_len > 0) {

			a_size = ocfs2_xattr_entry_real_size(0, acl_len);

			if (S_ISDIR(mode))

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