On 05/31/2013 04:59:49 PM, Geoffrey Thomas wrote:
BIO_BARRIER was removed a while ago, and barrier.txt was removed in
04ccc65cd1f57aee861708e08cd2272c5a0d088c. Replace the section
referring
to those with a summary of writeback_cache_control.txt and a pointer
to
it.
Signed-off-by: Geoffrey Thomas <gthomas@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
---
Let me know if I got this text right -- I don't pretend to be
familiar with
any of this, and simply just noticed this while reading the
documentation to
try to understand it.
Looks good, couple of typos:
+In order to ensure consistency of journaled filesystems and implement
+fsync and similar operations, the block layer provides two methods
for
+synchronizing volatile writeback caches to non-volatile storage. Both
+are invoked via flags on an i/o operation. The first flag, REQ_FLUSH,
+requires that all previously completed writes be reach to
non-volatile
be reach to?
+ struct request **tag_index; /* map of busy tags */
+ unsigned long *tag_map; /* map of free/busy
tags */
What's the difference between these two entries? In the second, does
the bit being set indicate that it's free or that it's busy?
+ int busy; /* current depth */
+ int max_depth; /* what we will send to
device */
+ int real_max_depth; /* what the array can
hold */
So current is not what we're actually sending?
Did the meanings of these fields change, or did you just change the
comments?
On the whole it looks great...
Rob--
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