Re: [f2fs-dev] [PATCH] f2fs:Fix concurrent access issues in the function recover_dentry

[Chao Yu]

> On Aug 8, 2015, at 11:12 AM, Nicholas Krause <xerofoify@xxxxxxxxx> wrote:
> 
> This fixes concurrent access issues in the function recover_dentry
> by locking and locking another the block labeled retry with the
> functions f2fs_lock_op/f2fs_unlock_op on a pointer of the
> superblock used by the passed inode structure pointer by this

Recovery and checkpoint will block each other with cp_mutex firstly,
so f2fs_lock_all in its only caller checkpoint have no chance to race
with any f2fs_lock_op in recovery procedure.

Itâs not needed to call f2fs_lock_op here.

Thanks,

> 
> Signed-off-by: Nicholas Krause <xerofoify@xxxxxxxxx>
> ---
> fs/f2fs/recovery.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index 24a8c1d..b86ea29 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -70,6 +70,7 @@ static struct fsync_inode_entry *get_fsync_inode(struct list_head *head,
> static int recover_dentry(struct inode *inode, struct page *ipage)
> {
> 	struct f2fs_inode *raw_inode = F2FS_INODE(ipage);
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> 	nid_t pino = le32_to_cpu(raw_inode->i_pino);
> 	struct f2fs_dir_entry *de;
> 	struct qstr name;
> @@ -97,6 +98,7 @@ static int recover_dentry(struct inode *inode, struct page *ipage)
> 		goto out_err;
> 	}
> retry:
> +	f2fs_lock_op(sbi);
> 	de = f2fs_find_entry(dir, &name, &page);
> 	if (de && inode->i_ino == le32_to_cpu(de->ino))
> 		goto out_unmap_put;
> @@ -117,6 +119,7 @@ retry:
> 		}
> 		f2fs_delete_entry(de, page, dir, einode);
> 		iput(einode);
> +		f2fs_unlock_op(sbi);
> 		goto retry;
> 	}
> 	err = __f2fs_add_link(dir, &name, inode, inode->i_ino, inode->i_mode);
> @@ -129,7 +132,8 @@ retry:
> 		add_dirty_dir_inode(dir);
> 		set_inode_flag(F2FS_I(dir), FI_DELAY_IPUT);
> 	}
> -
> +
> +	f2fs_unlock_op(sbi);
> 	goto out;
> 
> out_unmap_put:
> -- 
> 2.1.4
> 
> 
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