Re: f2fs: BUG_ON() is triggered when mount valid f2fs filesystem

[Andrey Tsyvarev <tsyvarev@ispras.ru>]

Hi,

With this patch mounting of the image continues to fail (with similar 
BUG_ON).
But when image is formatted again (and steps mentioned in the previous 
message are performed),
mounting of it is now succeed.

Is this is a true purpose of the patch?

15.04.2014 15:04, Jaegeuk Kim пишет:
> Hi,
>
> Thank you for the report.
> I retrieved the fault image and found out that previous garbage data
> wreak such the wrong behaviors.
> So, I wrote the following patch that fills one zero-block at the
> checkpoint procedure.
> If the underlying device supports discard, I expect that it mostly
> doesn't incur any performance regression significantly.
>
> Could you test this patch?
>
> >From 60588ceb7277aae2a79e7f67f5217d1256720d78 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> Date: Tue, 15 Apr 2014 13:57:55 +0900
> Subject: [PATCH] f2fs: avoid to conduct roll-forward due to the remained
>   garbage blocks
>
> The f2fs always scans the next chain of direct node blocks.
> But some garbage blocks are able to be remained due to no discard
> support or
> SSR triggers.
> This occasionally wreaks recovering wrong inodes that were used or
> BUG_ONs
> due to reallocating node ids as follows.
>
> When mount this f2fs image:
> http://linuxtesting.org/downloads/f2fs_fault_image.zip
> BUG_ON is triggered in f2fs driver (messages below are generated on
> kernel 3.13.2; for other kernels output is similar):
>
> kernel BUG at fs/f2fs/node.c:215!
>   Call Trace:
>   [<ffffffffa032ebad>] recover_inode_page+0x1fd/0x3e0 [f2fs]
>   [<ffffffff811446e7>] ? __lock_page+0x67/0x70
>   [<ffffffff81089990>] ? autoremove_wake_function+0x50/0x50
>   [<ffffffffa0337788>] recover_fsync_data+0x1398/0x15d0 [f2fs]
>   [<ffffffff812b9e5c>] ? selinux_d_instantiate+0x1c/0x20
>   [<ffffffff811cb20b>] ? d_instantiate+0x5b/0x80
>   [<ffffffffa0321044>] f2fs_fill_super+0xb04/0xbf0 [f2fs]
>   [<ffffffff811b861e>] ? mount_bdev+0x7e/0x210
>   [<ffffffff811b8769>] mount_bdev+0x1c9/0x210
>   [<ffffffffa0320540>] ? validate_superblock+0x210/0x210 [f2fs]
>   [<ffffffffa031cf8d>] f2fs_mount+0x1d/0x30 [f2fs]
>   [<ffffffff811b9497>] mount_fs+0x47/0x1c0
>   [<ffffffff81166e00>] ? __alloc_percpu+0x10/0x20
>   [<ffffffff811d4032>] vfs_kern_mount+0x72/0x110
>   [<ffffffff811d6763>] do_mount+0x493/0x910
>   [<ffffffff811615cb>] ? strndup_user+0x5b/0x80
>   [<ffffffff811d6c70>] SyS_mount+0x90/0xe0
>   [<ffffffff8166f8d9>] system_call_fastpath+0x16/0x1b
>
> Found by Linux File System Verification project (linuxtesting.org).
>
> Reported-by: Andrey Tsyvarev <tsyvarev@ispras.ru>
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> ---
>   fs/f2fs/checkpoint.c |  6 ++++++
>   fs/f2fs/f2fs.h       |  1 +
>   fs/f2fs/segment.c    | 17 +++++++++++++++--
>   3 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 4aa521a..890e23d 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -762,6 +762,12 @@ static void do_checkpoint(struct f2fs_sb_info *sbi,
> bool is_umount)
>   	void *kaddr;
>   	int i;
>   
> +	/*
> +	 * This avoids to conduct wrong roll-forward operations and uses
> +	 * metapages, so should be called prior to sync_meta_pages below.
> +	 */
> +	discard_next_dnode(sbi);
> +
>   	/* Flush all the NAT/SIT pages */
>   	while (get_pages(sbi, F2FS_DIRTY_META))
>   		sync_meta_pages(sbi, META, LONG_MAX);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 2ecac83..2c5a5da 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1179,6 +1179,7 @@ int f2fs_issue_flush(struct f2fs_sb_info *);
>   void invalidate_blocks(struct f2fs_sb_info *, block_t);
>   void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t);
>   void clear_prefree_segments(struct f2fs_sb_info *);
> +void discard_next_dnode(struct f2fs_sb_info *);
>   int npages_for_summary_flush(struct f2fs_sb_info *);
>   void allocate_new_segments(struct f2fs_sb_info *);
>   struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 1e264e7..9993f94 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -335,13 +335,26 @@ static void locate_dirty_segment(struct
> f2fs_sb_info *sbi, unsigned int segno)
>   	mutex_unlock(&dirty_i->seglist_lock);
>   }
>   
> -static void f2fs_issue_discard(struct f2fs_sb_info *sbi,
> +static int f2fs_issue_discard(struct f2fs_sb_info *sbi,
>   				block_t blkstart, block_t blklen)
>   {
>   	sector_t start = SECTOR_FROM_BLOCK(sbi, blkstart);
>   	sector_t len = SECTOR_FROM_BLOCK(sbi, blklen);
> -	blkdev_issue_discard(sbi->sb->s_bdev, start, len, GFP_NOFS, 0);
>   	trace_f2fs_issue_discard(sbi->sb, blkstart, blklen);
> +	return blkdev_issue_discard(sbi->sb->s_bdev, start, len, GFP_NOFS, 0);
> +}
> +
> +void discard_next_dnode(struct f2fs_sb_info *sbi)
> +{
> +	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
> +	block_t blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
> +
> +	if (f2fs_issue_discard(sbi, blkaddr, 1)) {
> +		struct page *page = grab_meta_page(sbi, blkaddr);
> +		/* zero-filled page */
> +		set_page_dirty(page);
> +		f2fs_put_page(page, 1);
> +	}
>   }
>   
>   static void add_discard_addrs(struct f2fs_sb_info *sbi,

-- 
Andrey Tsyvarev  <tsyvarev@ispras.ru>