In get_lock_data_page, if there is a data race between get_dnode_of_data for
node and grab_cache_page for data, f2fs is able to face with the following
BUG_ON(dn.data_blkaddr == NEW_ADDR).
kernel BUG at /home/zeus/f2fs_test/src/fs/f2fs/data.c:251!
[<ffffffffa044966c>] get_lock_data_page+0x1ec/0x210 [f2fs]
Call Trace:
[<ffffffffa043b089>] f2fs_readdir+0x89/0x210 [f2fs]
[<ffffffff811a0920>] ? fillonedir+0x100/0x100
[<ffffffff811a0920>] ? fillonedir+0x100/0x100
[<ffffffff811a07f8>] vfs_readdir+0xb8/0xe0
[<ffffffff811a0b4f>] sys_getdents+0x8f/0x110
[<ffffffff816d7999>] system_call_fastpath+0x16/0x1b
This bug is able to be occurred when the block address of the data block is
changed after f2fs_put_dnode().
In order to avoid that, this patch fixes the lock order of node and data
blocks in which the node block lock is covered by the data block lock.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
---
fs/f2fs/data.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 91ff93b..05fb5c6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -233,18 +233,23 @@ struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
struct page *page;
int err;
+repeat:
+ page = grab_cache_page(mapping, index);
+ if (!page)
+ return ERR_PTR(-ENOMEM);
+
set_new_dnode(&dn, inode, NULL, NULL, 0);
err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
- if (err)
+ if (err) {
+ f2fs_put_page(page, 1);
return ERR_PTR(err);
+ }
f2fs_put_dnode(&dn);
- if (dn.data_blkaddr == NULL_ADDR)
+ if (dn.data_blkaddr == NULL_ADDR) {
+ f2fs_put_page(page, 1);
return ERR_PTR(-ENOENT);
-repeat:
- page = grab_cache_page(mapping, index);
- if (!page)
- return ERR_PTR(-ENOMEM);
+ }
if (PageUptodate(page))
return page;
--
1.8.1.3.566.gaa39828
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