2013-05-15 (수), 13:04 +0900, Namjae Jeon:
> 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 ?
For the data consistency, I'd like to check index in its node block
prior to this.
Thanks,
>
> Thanks.
> > --
> > 1.8.1.3.566.gaa39828
> >
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--
Jaegeuk Kim
Samsung
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