Hi Jaegeuk, > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > Sent: Tuesday, August 18, 2015 4:46 PM > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > Cc: Jaegeuk Kim > Subject: [f2fs-dev] [PATCH 5/5] f2fs: check the node block address of newly allocated nid > > This patch adds a routine which checks the block address of newly allocated nid. > If an nid has already allocated by other thread due to subtle data races, it > will result in filesystem corruption. > So, it needs to check whether its block address was already allocated or not > in prior to nid allocation as the last chance. > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > --- > fs/f2fs/node.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index 3cc32b8..6bef5a2 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -1573,6 +1573,8 @@ retry: > > /* We should not use stale free nids created by build_free_nids */ > if (nm_i->fcnt && !on_build_free_nids(nm_i)) { > + struct node_info ni; > + > f2fs_bug_on(sbi, list_empty(&nm_i->free_nid_list)); > list_for_each_entry(i, &nm_i->free_nid_list, list) > if (i->state == NID_NEW) > @@ -1583,6 +1585,13 @@ retry: > i->state = NID_ALLOC; > nm_i->fcnt--; > spin_unlock(&nm_i->free_nid_list_lock); > + > + /* check nid is allocated already */ > + get_node_info(sbi, *nid, &ni); > + if (ni.blk_addr != NULL_ADDR) { I didn't get it, why free nid is with non-NULL blkaddr? Could you please explain more about this? > + alloc_nid_done(sbi, *nid); Will another thread call alloc_nid_done too, making this free nid being released again? Thanks, > + goto retry; > + } > return true; > } > spin_unlock(&nm_i->free_nid_list_lock); > -- > 2.1.1 > > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
