cvs commit: src/sys/ufs/ufs ufs_lookup.c

[Eric Anderson]

Ruslan Ermilov wrote:
> On Wed, Mar 08, 2006 at 03:16:25AM -0500, Kris Kennaway wrote:
>   
>> On Wed, Mar 08, 2006 at 09:06:32AM +0200, Ruslan Ermilov wrote:
>>     
>>> On Wed, Mar 08, 2006 at 02:14:39AM +0000, Tor Egge wrote:
>>>       
>>>> tegge       2006-03-08 02:14:39 UTC
>>>>
>>>>   FreeBSD src repository
>>>>
>>>>   Modified files:
>>>>     sys/ufs/ufs          ufs_lookup.c 
>>>>   Log:
>>>>   Don't set IN_CHANGE and IN_UPDATE on inodes for potentially suspended
>>>>   file systems.  This could cause deadlocks when creating snapshots.
>>>>   
>>>>   Reviewed by:    jeff
>>>>   
>>>>   Revision  Changes    Path
>>>>   1.80      +0 -1      src/sys/ufs/ufs/ufs_lookup.c
>>>>
>>>>         
>>> Like for example "ls -l /filesystem/.snap" when "fsck -B" is in place?
>>>       
>> Is that a deadlock, or just the process being suspended until fsck
>> finishes?
>>     

I think the only options we have to fix this is to either make the .snap
directory 'hidden' (which is not a feature yet), or to possibly cache
the inode information on parent directories containing snapshots, so
when a fs is suspended or a snapshot is in progress, a stat of the
parent directory of the snapshots' doesn't block until the snapshot
finishes.

There has been brief discussion on freebsd-fs@ about adding a 'hidden'
flag (usable with chflags) to files and directories, and tools like ls,
etc, that would normally stat each file/dir in a directory would ignore,
unless a special option was used.  That would not stop other tools doing
stat calls from seeing it though, but I think most of the blocking
happens when a user does an ls -al in the directory.


Eric




-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
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