On Nov 11, 2019, at 8:29 PM, Theodore Ts'o <tytso@xxxxxxx> wrote: > > If the file system is corrupted such that a file's i_links_count is > too small, then it's possible that when unlinking that file, i_nlink > will already be zero. Previously we were working around this kind of > corruption by forcing i_nlink to one; but we were doing this before > trying to delete the directory entry --- and if the file system is > corrupted enough that ext4_delete_entry() fails, then we exit with > i_nlink elevated, and this causes the orphan inode list handling to be > FUBAR'ed, such that when we unmount the file system, the orphan inode > list can get corrupted. > > A better way to fix this is to simply skip trying to call drop_nlink() > if i_nlink is already zero, thus moving the check to the place where > it makes the most sense. > > https://bugzilla.kernel.org/show_bug.cgi?id=205433 > > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> > Cc: stable@xxxxxxxxxx > --- > fs/ext4/namei.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-) > > diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c > index a67cae3c8ff5..a856997d87b5 100644 > --- a/fs/ext4/namei.c > +++ b/fs/ext4/namei.c > @@ -3196,18 +3196,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry) > if (IS_DIRSYNC(dir)) > ext4_handle_sync(handle); > > - if (inode->i_nlink == 0) { > - ext4_warning_inode(inode, "Deleting file '%.*s' with no links", > - dentry->d_name.len, dentry->d_name.name); > - set_nlink(inode, 1); > - } > retval = ext4_delete_entry(handle, dir, de, bh); > if (retval) > goto end_unlink; > dir->i_ctime = dir->i_mtime = current_time(dir); > ext4_update_dx_flag(dir); > ext4_mark_inode_dirty(handle, dir); > - drop_nlink(inode); > + if (inode->i_nlink == 0) > + ext4_warning_inode(inode, "Deleting file '%.*s' with no links", > + dentry->d_name.len, dentry->d_name.name); > + else > + drop_nlink(inode); > if (!inode->i_nlink) > ext4_orphan_add(handle, inode); > inode->i_ctime = current_time(inode); > -- > 2.23.0 > Cheers, Andreas
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