Mystery solved? files not written for days...

[Felix Blyakher]

On Mar 30, 2009, at 5:01 PM, Eric Sandeen wrote:

> On LKML:
>
> [PATCH] writeback: guard against jiffies wraparound on
> inode->dirtied_when checks

The "jiffies wraparound" sounds very familiar, but I
thought it's been fixed ages ago.

> When a file is continually dirtied, the check in sync_sb_inodes:
>
>        /* Was this inode dirtied after sync_sb_inodes was called? */
>        if (time_after(inode->dirtied_when, start))
>                break;
>
> may have large windows where this trips on the first
> (continually-dirtied) inode on the list when the time_after check has
> wrapped, causing the nothing to be written out for that superblock,
> potentially for days.
>
> Could this be the reason for those various "hey, my file disappeared
> after a crash and I hadn't written to it for *days*" reports we got  
> now
> and then, leaving us all scratching our heads?

The "jiffies wraparound" could definitely cause this.

Felix

>
>
> -Eric
>
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