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authorNick Piggin <npiggin@suse.de>2007-07-19 01:46:59 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 10:04:41 -0700
commit54cb8821de07f2ffcd28c380ce9b93d5784b40d7 (patch)
tree1de676534963d96af42863b20191bc9f80060dea /include
parentd00806b183152af6d24f46f0c33f14162ca1262a (diff)
mm: merge populate and nopage into fault (fixes nonlinear)
Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes the virtual address -> file offset differently from linear mappings. ->populate is a layering violation because the filesystem/pagecache code should need to know anything about the virtual memory mapping. The hitch here is that the ->nopage handler didn't pass down enough information (ie. pgoff). But it is more logical to pass pgoff rather than have the ->nopage function calculate it itself anyway (because that's a similar layering violation). Having the populate handler install the pte itself is likewise a nasty thing to be doing. This patch introduces a new fault handler that replaces ->nopage and ->populate and (later) ->nopfn. Most of the old mechanism is still in place so there is a lot of duplication and nice cleanups that can be removed if everyone switches over. The rationale for doing this in the first place is that nonlinear mappings are subject to the pagefault vs invalidate/truncate race too, and it seemed stupid to duplicate the synchronisation logic rather than just consolidate the two. After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in pagecache. Seems like a fringe functionality anyway. NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no users have hit mainline yet. [akpm@linux-foundation.org: cleanup] [randy.dunlap@oracle.com: doc. fixes for readahead] [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h41
1 files changed, 34 insertions, 7 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ca9536a348c..f28a1b3e63a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -173,6 +173,7 @@ extern unsigned int kobjsize(const void *objp);
* In this case, do_no_page must
* return with the page locked.
*/
+#define VM_CAN_NONLINEAR 0x10000000 /* Has ->fault & does nonlinear pages */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -196,6 +197,25 @@ extern unsigned int kobjsize(const void *objp);
*/
extern pgprot_t protection_map[16];
+#define FAULT_FLAG_WRITE 0x01
+#define FAULT_FLAG_NONLINEAR 0x02
+
+/*
+ * fault_data is filled in the the pagefault handler and passed to the
+ * vma's ->fault function. That function is responsible for filling in
+ * 'type', which is the type of fault if a page is returned, or the type
+ * of error if NULL is returned.
+ *
+ * pgoff should be used in favour of address, if possible. If pgoff is
+ * used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get
+ * nonlinear mapping support.
+ */
+struct fault_data {
+ unsigned long address;
+ pgoff_t pgoff;
+ unsigned int flags;
+ int type;
+};
/*
* These are the virtual MM functions - opening of an area, closing and
@@ -205,9 +225,15 @@ extern pgprot_t protection_map[16];
struct vm_operations_struct {
void (*open)(struct vm_area_struct * area);
void (*close)(struct vm_area_struct * area);
- struct page * (*nopage)(struct vm_area_struct * area, unsigned long address, int *type);
- unsigned long (*nopfn)(struct vm_area_struct * area, unsigned long address);
- int (*populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
+ struct page *(*fault)(struct vm_area_struct *vma,
+ struct fault_data *fdata);
+ struct page *(*nopage)(struct vm_area_struct *area,
+ unsigned long address, int *type);
+ unsigned long (*nopfn)(struct vm_area_struct *area,
+ unsigned long address);
+ int (*populate)(struct vm_area_struct *area, unsigned long address,
+ unsigned long len, pgprot_t prot, unsigned long pgoff,
+ int nonblock);
/* notification that a previously read-only page is about to become
* writable, if an error is returned it will cause a SIGBUS */
@@ -661,7 +687,6 @@ static inline int page_mapped(struct page *page)
*/
#define NOPAGE_SIGBUS (NULL)
#define NOPAGE_OOM ((struct page *) (-1))
-#define NOPAGE_REFAULT ((struct page *) (-2)) /* Return to userspace, rerun */
/*
* Error return values for the *_nopfn functions
@@ -1110,9 +1135,11 @@ extern void truncate_inode_pages_range(struct address_space *,
loff_t lstart, loff_t lend);
/* generic vm_area_ops exported for stackable file systems */
-extern struct page *filemap_nopage(struct vm_area_struct *, unsigned long, int *);
-extern int filemap_populate(struct vm_area_struct *, unsigned long,
- unsigned long, pgprot_t, unsigned long, int);
+extern struct page *filemap_fault(struct vm_area_struct *, struct fault_data *);
+extern struct page * __deprecated_for_modules
+filemap_nopage(struct vm_area_struct *, unsigned long, int *);
+extern int __deprecated_for_modules filemap_populate(struct vm_area_struct *,
+ unsigned long, unsigned long, pgprot_t, unsigned long, int);
/* mm/page-writeback.c */
int write_one_page(struct page *page, int wait);