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Subject[RFC] f2fs: fix a race condition between evict & gc
Date
When collecting data segment(gc_data_segment), there is a race condition
between evict and phases of gc:
0) ra_node_page(dnode)
1) ra_node_page(inode)
<--- evict the inode
2) f2fs_iget get the inode and add it to gc_list
3) move_data_page

In step 2), f2fs_iget does NOT find the inode and allocs a new inode as result,
which is not resonable.

This patch changes f2fs_iget to ilookup. when no inode is found, no new inode is
created.

Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
---
fs/f2fs/gc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 38d56f6..6e73193 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -717,8 +717,8 @@ next_step:
ofs_in_node = le16_to_cpu(entry->ofs_in_node);

if (phase == 2) {
- inode = f2fs_iget(sb, dni.ino);
- if (IS_ERR(inode) || is_bad_inode(inode))
+ inode = ilookup(sb, dni.ino);
+ if (!inode || IS_ERR(inode) || is_bad_inode(inode))
continue;

/* if encrypted inode, let's go phase 3 */
--
1.9.1
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