2006-12-06 23:37:56

by Eric Sandeen

[permalink] [raw]
Subject: [RFC][PATCH] process orphan list if device transitions to readonly

I have a patch in -mm now to skip orphan inode processing on a read-only
device (where IO may fail if issued), but Stephen points out that if
the device ever transitions back to readwrite, and the filesystem is
remounted as rewrite, we should process the orphan inode list at that point.

Today, I'm not sure how we can easily get into this situation - for example,
lvm apparently cannot transform a RO snapshot into RW. But it is at least
possible to do this. For example I tested by:

create orphan list
mark block device RO via BLKROSET
mount fs RO
mark block device RW via BLKROSET
remount fs RW

so it's within the realm of possibility, certainly.

here's what I came up with; I'm not very pleased with it though, but I need
some way to let ext3_orphan_del know that the sb is already locked and it's
safe to do this orphan processing w/o re-taking it, so I added a state flag...




Signed-off-by: Eric Sandeen <[email protected]>

Index: linux-2.6.19/fs/ext3/namei.c
--- linux-2.6.19.orig/fs/ext3/namei.c
+++ linux-2.6.19/fs/ext3/namei.c
@@ -1942,15 +1942,15 @@ int ext3_orphan_del(handle_t *handle, st
struct ext3_iloc iloc;
int err = 0;

- lock_super(inode->i_sb);
- if (list_empty(&ei->i_orphan)) {
- unlock_super(inode->i_sb);
- return 0;
- }
+ sbi = EXT3_SB(inode->i_sb);
+ if (!(sbi->s_mount_state & EXT3_REMOUNTING_FS))
+ lock_super(inode->i_sb);
+ if (list_empty(&ei->i_orphan))
+ goto out;

ino_next = NEXT_ORPHAN(inode);
prev = ei->i_orphan.prev;
- sbi = EXT3_SB(inode->i_sb);

jbd_debug(4, "remove inode %lu from orphan list\n", inode->i_ino);

@@ -1996,7 +1996,8 @@ int ext3_orphan_del(handle_t *handle, st
ext3_std_error(inode->i_sb, err);
- unlock_super(inode->i_sb);
+ if (!(sbi->s_mount_state & EXT3_REMOUNTING_FS))
+ unlock_super(inode->i_sb);
return err;

Index: linux-2.6.19/fs/ext3/super.c
--- linux-2.6.19.orig/fs/ext3/super.c
+++ linux-2.6.19/fs/ext3/super.c
@@ -2358,6 +2358,10 @@ static int ext3_remount (struct super_bl
goto restore_opts;
if (!ext3_setup_super (sb, es, 0))
sb->s_flags &= ~MS_RDONLY;
+ EXT3_SB(sb)->s_mount_state |= (EXT3_ORPHAN_FS|EXT3_REMOUNTING_FS);
+ ext3_orphan_cleanup(sb, es);
+ EXT3_SB(sb)->s_mount_state &= ~(EXT3_ORPHAN_FS|EXT3_REMOUNTING_FS);
Index: linux-2.6.19/include/linux/ext3_fs.h
--- linux-2.6.19.orig/include/linux/ext3_fs.h
+++ linux-2.6.19/include/linux/ext3_fs.h
@@ -356,6 +356,7 @@ struct ext3_inode {
#define EXT3_VALID_FS 0x0001 /* Unmounted cleanly */
#define EXT3_ERROR_FS 0x0002 /* Errors detected */
#define EXT3_ORPHAN_FS 0x0004 /* Orphans being recovered */
+#define EXT3_REMOUNTING_FS 0x0008 /* Filesystem remounting, sb locked */

* Mount flags