The patch titled Subject: nilfs2: fix nilfs_empty_dir() misjudgment and long loop on I/O errors has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-fix-nilfs_empty_dir-misjudgment-and-long-loop-on-i-o-errors.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Ryusuke Konishi konishi.ryusuke@gmail.com Subject: nilfs2: fix nilfs_empty_dir() misjudgment and long loop on I/O errors Date: Tue, 4 Jun 2024 22:42:55 +0900

The error handling in nilfs_empty_dir() when a directory folio/page read fails is incorrect, as in the old ext2 implementation, and if the folio/page cannot be read or nilfs_check_folio() fails, it will falsely determine the directory as empty and corrupt the file system.

In addition, since nilfs_empty_dir() does not immediately return on a failed folio/page read, but continues to loop, this can cause a long loop with I/O if i_size of the directory's inode is also corrupted, causing the log writer thread to wait and hang, as reported by syzbot.

Fix these issues by making nilfs_empty_dir() immediately return a false value (0) if it fails to get a directory folio/page.

Link: https://lkml.kernel.org/r/20240604134255.7165-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+c8166c541d3971bf6c87@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c8166c541d3971bf6c87 Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations") Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/nilfs2/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/nilfs2/dir.c~nilfs2-fix-nilfs_empty_dir-misjudgment-and-long-loop-on-i-o-errors +++ a/fs/nilfs2/dir.c @@ -607,7 +607,7 @@ int nilfs_empty_dir(struct inode *inode)

kaddr = nilfs_get_folio(inode, i, &folio); if (IS_ERR(kaddr)) - continue; + return 0;

de = (struct nilfs_dir_entry *)kaddr; kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1); _

Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-fix-potential-kernel-bug-due-to-lack-of-writeback-flag-waiting.patch nilfs2-fix-nilfs_empty_dir-misjudgment-and-long-loop-on-i-o-errors.patch