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Add bowrite.

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Bowrite guarantees that buffers queued after a call to bowrite will
be written after the specified buffer (on a particular device).
Bowrite does this either by taking advantage of hardware ordering support
(e.g. tagged queueing on SCSI devices) or resorting to a synchronous write.
This commit is contained in:
Justin T. Gibbs 1996-09-06 05:37:53 +00:00
parent 23da239df6
commit 0b64164fca
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=18070
1 changed files with 17 additions and 2 deletions
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19
sys/kern/vfs_bio.c
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@ -18,7 +18,7 @@
* 5. Modifications may be freely made to this file if the above conditions
* are met.
*
* $Id: vfs_bio.c,v 1.95 1996/08/04 20:13:08 phk Exp $
* $Id: vfs_bio.c,v 1.96 1996/08/21 21:55:18 dyson Exp $
*/
/*
@ -313,7 +313,7 @@ bwrite(struct buf * bp)
curproc->p_stats->p_ru.ru_oublock++;
VOP_STRATEGY(bp);
if ((oldflags & B_ASYNC) == 0) {
if ((bp->b_flags & B_ASYNC) == 0) {
int rtval = biowait(bp);
if (oldflags & B_DELWRI) {
@ -398,6 +398,21 @@ bawrite(struct buf * bp)
(void) VOP_BWRITE(bp);
}
/*
* Ordered write.
* Start output on a buffer, but only wait for it to complete if the
* output device cannot guarantee ordering in some other way. Devices
* that can perform asyncronous ordered writes will set the B_ASYNC
* flag in their strategy routine.
* The buffer is released when the output completes.
*/
int
bowrite(struct buf * bp)
{
bp->b_flags |= B_ORDERED;
return (VOP_BWRITE(bp));
}
/*
* Release a buffer.
*/