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correct read-ahead calculations in vfs_bio_getpages

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Previously the calculations were done as if the requested region
ended at the start of the last requested page, not its end.
The problem as actually quite minor as it affected only stats and
page prefaulting, not the actual page data, and only with specific
parameters.

Reviewed by:	kib (previous version)
MFC after:	2 weeks
This commit is contained in:
Andriy Gapon 2018-01-18 12:59:04 +00:00
parent ac97ccbab5
commit 3e4f610dad
1 changed files with 8 additions and 1 deletions
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9
sys/kern/vfs_bio.c
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@ -4802,7 +4802,14 @@ vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
la = IDX_TO_OFF(ma[count - 1]->pindex);
if (la >= object->un_pager.vnp.vnp_size)
return (VM_PAGER_BAD);
lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size;
/*
* Change the meaning of la from where the last requested page starts
* to where it ends, because that's the end of the requested region
* and the start of the potential read-ahead region.
*/
la += PAGE_SIZE;
lpart = la > object->un_pager.vnp.vnp_size;
bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
/*