2013/5/15, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>:
> 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;
Is there no need to move PageUptodate condition checking to
grab_cache_page next ?
Thanks.
> --
> 1.8.1.3.566.gaa39828
>
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