Do you understand the purpose of the freeze? It is to ensure the underlying block device is stable and consistent. I believe the primary in kernel user of freeze is device mapper (DM). DM effectively does: freeze create COW based snapshot unfreeze. Creation of a COW (copy on write) snapshot is extremely quick, so the freeze should only be in place for a very short period of time. Note that reads of the filesystem do not interfere with the above. Also, while frozen the filesystem is allowed to support a write cache, it just cannot forward the writes / inode creations / etc. down to the block device it is sitting on. Greg On Wed, Dec 31, 2008 at 10:06 AM, rishi agrawal <postrishi@xxxxxxxxx> wrote: > as far as i have understood it is not freezing the file system but it > is only freezing the write operation on block device > > had it been freezing the file system inode creation would also block > > > > On Wed, Dec 31, 2008 at 8:09 PM, rishi agrawal <postrishi@xxxxxxxxx> wrote: >> I used a kernel module to freeze the file system using the function freeze_bdev >> >> but when i am try to use touch command on the file system i am able to >> create the files. >> >> even read requests are served immediately >> >> only the write requests are being blocked >> >> until i call the thaw function >> >> can i have an explanation for this >> >> On Wed, Dec 31, 2008 at 6:11 PM, ajit mote <mail2blackmen@xxxxxxxxx> wrote: >>> Hello, >>> >>>> I want to freeze a file system. I have seen a field in vfs superblock >>>> s_frozen. >>>> >>>> But i am clue less about freezing the file system using that. >>> >>> >>> freeze_bdev function ( fs/buffer.c) lock a filesystem and force it into a >>> consistent state ... >>> Above function use s_frozen flag to freez the file system ... >>> >>>> >>>> >>>> >>>> -- >>>> Regards, >>>> Rishi B. Agrawal >>>> >>>> -- >>>> To unsubscribe from this list: send an email with >>>> "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx >>>> Please read the FAQ at http://kernelnewbies.org/FAQ >>>> >>> >>> >>> >>> -- >>> Thanks & Regards, >>> Ajit Subhash Mote >>> >>> >> >> >> >> -- >> Regards, >> Rishi B. Agrawal >> > > > > -- > Regards, > Rishi B. Agrawal > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
