f2fs: fix wrong BUG_ON condition

This patch removes a false-alaramed BUG_ON.
The previous BUG_ON condition didn't cover the following true scenario.

In f2fs_add_link, 1) get_new_data_page gives an uptodate page successfully,
and then, 2) init_inode_metadata returns -ENOSPC.
At this moment, a new clean data page is remained in the page cache, but its
block address still indicates NEW_ADDR.
After then, even if sync is called, this clean data page cannot be written to
the disk due to the clean state.

So this means that get_lock_data_page should make a new empty page when its
block address is NEW_ADDR and its page is not uptodated.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ea3cb29018e9..6b328de41728 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -259,8 +259,17 @@ repeat:
         if (PageUptodate(page))
                 return page;
 
-        BUG_ON(dn.data_blkaddr == NEW_ADDR);
-        BUG_ON(dn.data_blkaddr == NULL_ADDR);
+        /*
+         * A new dentry page is allocated but not able to be written, since its
+         * new inode page couldn't be allocated due to -ENOSPC.
+         * In such the case, its blkaddr can be remained as NEW_ADDR.
+         * see, f2fs_add_link -> get_new_data_page -> init_inode_metadata.
+         */
+        if (dn.data_blkaddr == NEW_ADDR) {
+                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+                SetPageUptodate(page);
+                return page;
+        }
 
         err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
         if (err)