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f2fs: fix the inconsistent state of data pages 

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@samsung.com>
This commit is contained in:
Jaegeuk Kim 2013-05-13 08:38:35 +09:00
parent 65e5cd0a15
commit 650495dedc
1 changed files with 13 additions and 8 deletions
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21
fs/f2fs/data.c
View File

@ -233,19 +233,24 @@ struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
struct page *page;
int err;
set_new_dnode(&dn, inode, NULL, NULL, 0);
err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
if (err)
return ERR_PTR(err);
f2fs_put_dnode(&dn);
if (dn.data_blkaddr == NULL_ADDR)
return ERR_PTR(-ENOENT);
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) {
f2fs_put_page(page, 1);
return ERR_PTR(err);
}
f2fs_put_dnode(&dn);
if (dn.data_blkaddr == NULL_ADDR) {
f2fs_put_page(page, 1);
return ERR_PTR(-ENOENT);
}
if (PageUptodate(page))
return page;