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dax: Finish fault completely when loading holes

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The only case when we do not finish the page fault completely is when we
are loading hole pages into a radix tree. Avoid this special case and
finish the fault in that case as well inside the DAX fault handler. It
will allow us for easier iomap handling.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Jan Kara 2016-10-19 14:48:38 +02:00 • committed by Dan Williams
parent e3fce68cdb
commit f449b936f1
1 changed files with 18 additions and 9 deletions
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27
fs/dax.c
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@ -539,15 +539,16 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
* otherwise it will simply fall out of the page cache under memory * otherwise it will simply fall out of the page cache under memory
* pressure without ever having been dirtied. * pressure without ever having been dirtied.
*/ */
static int dax_load_hole(struct address_space *mapping, void *entry, static int dax_load_hole(struct address_space *mapping, void **entry,
struct vm_fault *vmf) struct vm_fault *vmf)
{ {
struct page *page; struct page *page;
int ret;
/* Hole page already exists? Return it... */ /* Hole page already exists? Return it... */
if (!radix_tree_exceptional_entry(entry)) { if (!radix_tree_exceptional_entry(*entry)) {
vmf->page = entry; page = *entry;
return VM_FAULT_LOCKED; goto out;
} }
/* This will replace locked radix tree entry with a hole page */ /* This will replace locked radix tree entry with a hole page */
@ -555,8 +556,17 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
vmf->gfp_mask | __GFP_ZERO); vmf->gfp_mask | __GFP_ZERO);
if (!page) if (!page)
return VM_FAULT_OOM; return VM_FAULT_OOM;
out:
vmf->page = page; vmf->page = page;
return VM_FAULT_LOCKED; ret = finish_fault(vmf);
vmf->page = NULL;
*entry = page;
if (!ret) {
/* Grab reference for PTE that is now referencing the page */
get_page(page);
return VM_FAULT_NOPAGE;
}
return ret;
} }
static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
@ -1163,8 +1173,8 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
case IOMAP_UNWRITTEN: case IOMAP_UNWRITTEN:
case IOMAP_HOLE: case IOMAP_HOLE:
if (!(vmf->flags & FAULT_FLAG_WRITE)) { if (!(vmf->flags & FAULT_FLAG_WRITE)) {
vmf_ret = dax_load_hole(mapping, entry, vmf); vmf_ret = dax_load_hole(mapping, &entry, vmf);
break; goto finish_iomap;
} }
/*FALLTHRU*/ /*FALLTHRU*/
default: default:
@ -1185,8 +1195,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
} }
} }
unlock_entry: unlock_entry:
if (vmf_ret != VM_FAULT_LOCKED || error) put_locked_mapping_entry(mapping, vmf->pgoff, entry);
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
out: out:
if (error == -ENOMEM) if (error == -ENOMEM)
return VM_FAULT_OOM | major; return VM_FAULT_OOM | major;