2013/5/15, Jaegeuk Kim <[email protected]>: > 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 <[email protected]> > --- > 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 ?
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