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Fixed "bufspace" calculation. It was lossy in some circumstances of the

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buffer resizing and caused a "newbuf" deadlock.

Reviewed by:	John Dyson & David Greenman
Submitted by:	Peter Wemm
This commit is contained in:
David Greenman 1995-07-17 06:26:07 +00:00
parent 208ed9d8aa
commit 1ce781c3af
1 changed files with 5 additions and 14 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 1.47 1995/06/28 12:00:54 davidg Exp $
* $Id: vfs_bio.c,v 1.48 1995/07/15 16:01:46 davidg Exp $
*/
/*
@ -934,21 +934,16 @@ allocbuf(struct buf * bp, int size)
mbsize = ((size + DEV_BSIZE - 1) / DEV_BSIZE) * DEV_BSIZE;
newbsize = round_page(size);
if (newbsize == bp->b_bufsize) {
bp->b_bcount = size;
return 1;
} else if (newbsize < bp->b_bufsize) {
if (newbsize < bp->b_bufsize) {
vm_hold_free_pages(
bp,
(vm_offset_t) bp->b_data + newbsize,
(vm_offset_t) bp->b_data + bp->b_bufsize);
bufspace -= (bp->b_bufsize - newbsize);
} else if (newbsize > bp->b_bufsize) {
vm_hold_load_pages(
bp,
(vm_offset_t) bp->b_data + bp->b_bufsize,
(vm_offset_t) bp->b_data + newbsize);
bufspace += (newbsize - bp->b_bufsize);
}
} else {
vm_page_t m;
@ -957,10 +952,7 @@ allocbuf(struct buf * bp, int size)
newbsize = ((size + DEV_BSIZE - 1) / DEV_BSIZE) * DEV_BSIZE;
desiredpages = round_page(newbsize) / PAGE_SIZE;
if (newbsize == bp->b_bufsize) {
bp->b_bcount = size;
return 1;
} else if (newbsize < bp->b_bufsize) {
if (newbsize < bp->b_bufsize) {
if (desiredpages < bp->b_npages) {
pmap_qremove((vm_offset_t) trunc_page(bp->b_data) +
desiredpages * PAGE_SIZE, (bp->b_npages - desiredpages));
@ -985,9 +977,8 @@ allocbuf(struct buf * bp, int size)
bp->b_pages[i] = NULL;
}
bp->b_npages = desiredpages;
bufspace -= (bp->b_bufsize - newbsize);
}
} else {
} else if (newbsize > bp->b_bufsize) {
vm_object_t obj;
vm_offset_t tinc, off, toff, objoff;
int pageindex, curbpnpages;
@ -1102,9 +1093,9 @@ allocbuf(struct buf * bp, int size)
pmap_qenter((vm_offset_t) bp->b_data, bp->b_pages, bp->b_npages);
bp->b_data += off % PAGE_SIZE;
}
bufspace += (newbsize - bp->b_bufsize);
}
}
bufspace += (newbsize - bp->b_bufsize);
bp->b_bufsize = newbsize;
bp->b_bcount = size;
return 1;