lkml.org 
[lkml]   [2019]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: btrfs: drop inode reference count on error path
From
Date


On 17.04.19 г. 5:23 ч., Pan Bian wrote:
> The reference count of inode is incremented by ihold. It should be
> dropped if not used. However, the reference count is not dropped if
> error occurs during updating the inode or deleting orphan items. This
> patch fixes the bug.
>
> Signed-off-by: Pan Bian <bianpan2016@163.com>

The extra reference count taken is needed for the call to d_instantiate,
while this operation is in progress the inode is actually locked. This
means it will be a lot clearer if ihold is done right before
d_instantiate and they are moved at the end of the function where we are
sure no errors have appened. Something like the attached diff

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 82fdda8ff5ab..5cc6529a549f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6579,7 +6579,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
u64 index;
int err;
- int drop_inode = 0;
+ int log_mode;

/* do not allow sys_link's with other subvols of the same device */
if (root->root_key.objectid != BTRFS_I(inode)->root->root_key.objectid)
@@ -6610,47 +6610,42 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
inc_nlink(inode);
inode_inc_iversion(inode);
inode->i_ctime = current_time(inode);
- ihold(inode);
set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);

err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
1, index);
+ if (err)
+ goto fail;

- if (err) {
- drop_inode = 1;
- } else {
- struct dentry *parent = dentry->d_parent;
- int ret;
-
- err = btrfs_update_inode(trans, root, inode);
+ err = btrfs_update_inode(trans, root, inode);
+ if (err)
+ goto fail;
+ if (inode->i_nlink == 1) {
+ /*
+ * If new hard link count is 1, it's a file created
+ * with open(2) O_TMPFILE flag.
+ */
+ err = btrfs_orphan_del(trans, BTRFS_I(inode));
+ if (err)
+ goto fail;
+ }
+ BTRFS_I(inode)->last_link_trans = trans->transid;
+ log_mode = btrfs_log_new_name(trans, BTRFS_I(inode), NULL,
+ dentry->d_parent, true, NULL);
+ if (log_mode == BTRFS_NEED_TRANS_COMMIT) {
+ err = btrfs_commit_transaction(trans);
+ trans = NULL;
if (err)
goto fail;
- if (inode->i_nlink == 1) {
- /*
- * If new hard link count is 1, it's a file created
- * with open(2) O_TMPFILE flag.
- */
- err = btrfs_orphan_del(trans, BTRFS_I(inode));
- if (err)
- goto fail;
- }
- BTRFS_I(inode)->last_link_trans = trans->transid;
- d_instantiate(dentry, inode);
- ret = btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent,
- true, NULL);
- if (ret == BTRFS_NEED_TRANS_COMMIT) {
- err = btrfs_commit_transaction(trans);
- trans = NULL;
- }
}

+ ihold(inode);
+ d_instantiate(dentry, inode);
fail:
if (trans)
btrfs_end_transaction(trans);
- if (drop_inode) {
+ if (err)
inode_dec_link_count(inode);
- iput(inode);
- }
btrfs_btree_balance_dirty(fs_info);
return err;
}
\
 
 \ /
  Last update: 2019-04-17 10:15    [W:0.046 / U:1.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site