So here is a little lesson I learnt while solving this problem. If you are relying on buffer caches for input/output or in other words you are in love with the __bread(bdev, block, size) function then be sure to set the value of bdev->bd_inode->i_blkbits to log (size) before calling __bread(). Obviously, the log I am talking about here is log to the base 2. If you do not do so, then the kernel may enter an infinite loop.
wish you happy hacking and a splendid new year!
- Abhishek
On 12/30/05, Thomas Petazzoni <thomas.petazzoni@xxxxxxxx> wrote:
Hi,
Abhishek Gupta wrote:
> I am having trouble in using the block cache apis at the driver level. I am
> writing a new radix tree target for LVM and for that I need to cache metadata
> blocks at the LVM layer. For these purposes I am using the __bread() function.
> The problem is that it works perfectly with loopback devices but the moment I
> try to use __bread() on an actual physical device, the whole machine freezes.
> Has anyone had this trouble before. I would really appreciate any help in this
> regard.
Is the code available somewhere ? Did you check the output of Sysrq-t ?
Sincerly,
Thomas
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Thomas Petazzoni
thomas.petazzoni@xxxxxxxx
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