Messages in this thread Patch in this message | | | Date | Tue, 10 Oct 2006 17:01:43 +0200 | From | Nick Piggin <> | Subject | Re: [rfc] 2.6.19-rc1-git5: consolidation of file backed fault handlers |
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On Tue, Oct 10, 2006 at 03:33:42PM +0100, Christoph Hellwig wrote: > On Tue, Oct 10, 2006 at 04:21:32PM +0200, Nick Piggin wrote: > > This patchset is against 2.6.19-rc1-mm1 up to > > numa-add-zone_to_nid-function-swap_prefetch.patch (ie. no readahead stuff, > > which causes big rejects and would be much easier to fix in readahead > > patches than here). Other than this feature, the -mm specific stuff is > > pretty simple (mainly straightforward filesystem conversions). > > > > Changes since last round: > > - trimmed the cc list, no big changes since last time. > > - fix the few buglets preventing it from actually booting > > - reinstate filemap_nopage and filemap_populate, because they're exported > > symbols even though no longer used in the tree. Schedule for removal. > > Just kill them and the whole ->populate methods. We have a better API that > replaces them 100% with your patch, and they've never been a widespread > API.
OK, this is what the patch looks like. I'm happy for .nopage to stay around for a while longer, because it costs us exactly 12 lines of code in mm/memory.c
Andrew?
-- Remove legacy filemap_nopage and all of the .populate API cruft.
include/linux/mm.h | 9 -- mm/filemap.c | 195 ----------------------------------------------------- mm/fremap.c | 71 ++----------------- mm/memory.c | 37 ++-------- 4 files changed, 21 insertions(+), 291 deletions(-)
Signed-off-by: Nick Piggin <npiggin@suse.de>
Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h +++ linux-2.6/include/linux/mm.h @@ -223,8 +223,6 @@ struct vm_operations_struct { void (*close)(struct vm_area_struct * area); 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); - 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 */ int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page); @@ -742,8 +740,6 @@ static inline void unmap_shared_mapping_ extern int vmtruncate(struct inode * inode, loff_t offset); extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end); -extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot); -extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot); #ifdef CONFIG_MMU extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, @@ -1053,10 +1049,7 @@ extern void truncate_inode_pages_range(s loff_t lstart, loff_t lend); /* generic vm_area_ops exported for stackable file systems */ -extern struct page * __deprecated filemap_fault(struct vm_area_struct *, struct fault_data *); -extern struct page * __deprecated 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 *); /* mm/page-writeback.c */ int write_one_page(struct page *page, int wait); Index: linux-2.6/mm/filemap.c =================================================================== --- linux-2.6.orig/mm/filemap.c +++ linux-2.6/mm/filemap.c @@ -1539,201 +1539,6 @@ page_not_uptodate: } EXPORT_SYMBOL(filemap_fault); -/* - * filemap_nopage and filemap_populate are legacy exports that are not used - * in tree. Scheduled for removal. - */ -struct page *filemap_nopage(struct vm_area_struct *area, - unsigned long address, int *type) -{ - struct page *page; - struct fault_data fdata; - fdata.address = address; - fdata.pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) - + area->vm_pgoff; - fdata.flags = 0; - - page = filemap_fault(area, &fdata); - if (type) - *type = fdata.type; - - return page; -} -EXPORT_SYMBOL(filemap_nopage); - -static struct page * filemap_getpage(struct file *file, unsigned long pgoff, - int nonblock) -{ - struct address_space *mapping = file->f_mapping; - struct page *page; - int error; - - /* - * Do we have something in the page cache already? - */ -retry_find: - page = find_get_page(mapping, pgoff); - if (!page) { - if (nonblock) - return NULL; - goto no_cached_page; - } - - /* - * Ok, found a page in the page cache, now we need to check - * that it's up-to-date. - */ - if (!PageUptodate(page)) { - if (nonblock) { - page_cache_release(page); - return NULL; - } - goto page_not_uptodate; - } - -success: - /* - * Found the page and have a reference on it. - */ - mark_page_accessed(page); - return page; - -no_cached_page: - error = page_cache_read(file, pgoff); - - /* - * The page we want has now been added to the page cache. - * In the unlikely event that someone removed it in the - * meantime, we'll just come back here and read it again. - */ - if (error >= 0) - goto retry_find; - - /* - * An error return from page_cache_read can result if the - * system is low on memory, or a problem occurs while trying - * to schedule I/O. - */ - return NULL; - -page_not_uptodate: - lock_page(page); - - /* Did it get truncated while we waited for it? */ - if (!page->mapping) { - unlock_page(page); - goto err; - } - - /* Did somebody else get it up-to-date? */ - if (PageUptodate(page)) { - unlock_page(page); - goto success; - } - - error = mapping->a_ops->readpage(file, page); - if (!error) { - wait_on_page_locked(page); - if (PageUptodate(page)) - goto success; - } else if (error == AOP_TRUNCATED_PAGE) { - page_cache_release(page); - goto retry_find; - } - - /* - * Umm, take care of errors if the page isn't up-to-date. - * Try to re-read it _once_. We do this synchronously, - * because there really aren't any performance issues here - * and we need to check for errors. - */ - lock_page(page); - - /* Somebody truncated the page on us? */ - if (!page->mapping) { - unlock_page(page); - goto err; - } - /* Somebody else successfully read it in? */ - if (PageUptodate(page)) { - unlock_page(page); - goto success; - } - - ClearPageError(page); - error = mapping->a_ops->readpage(file, page); - if (!error) { - wait_on_page_locked(page); - if (PageUptodate(page)) - goto success; - } else if (error == AOP_TRUNCATED_PAGE) { - page_cache_release(page); - goto retry_find; - } - - /* - * Things didn't work out. Return zero to tell the - * mm layer so, possibly freeing the page cache page first. - */ -err: - page_cache_release(page); - - return NULL; -} - -int filemap_populate(struct vm_area_struct *vma, unsigned long addr, - unsigned long len, pgprot_t prot, unsigned long pgoff, - int nonblock) -{ - struct file *file = vma->vm_file; - struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - unsigned long size; - struct mm_struct *mm = vma->vm_mm; - struct page *page; - int err; - - if (!nonblock) - force_page_cache_readahead(mapping, vma->vm_file, - pgoff, len >> PAGE_CACHE_SHIFT); - -repeat: - size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) - return -EINVAL; - - page = filemap_getpage(file, pgoff, nonblock); - - /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as - * done in shmem_populate calling shmem_getpage */ - if (!page && !nonblock) - return -ENOMEM; - - if (page) { - err = install_page(mm, vma, addr, page, prot); - if (err) { - page_cache_release(page); - return err; - } - } else if (vma->vm_flags & VM_NONLINEAR) { - /* No page was found just because we can't read it in now (being - * here implies nonblock != 0), but the page may exist, so set - * the PTE to fault it in later. */ - err = install_file_pte(mm, vma, addr, pgoff, prot); - if (err) - return err; - } - - len -= PAGE_SIZE; - addr += PAGE_SIZE; - pgoff++; - if (len) - goto repeat; - - return 0; -} -EXPORT_SYMBOL(filemap_populate); - struct vm_operations_struct generic_file_vm_ops = { .fault = filemap_fault, }; Index: linux-2.6/mm/fremap.c =================================================================== --- linux-2.6.orig/mm/fremap.c +++ linux-2.6/mm/fremap.c @@ -45,58 +45,10 @@ static int zap_pte(struct mm_struct *mm, } /* - * Install a file page to a given virtual memory address, release any - * previously existing mapping. - */ -int install_page(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long addr, struct page *page, pgprot_t prot) -{ - struct inode *inode; - pgoff_t size; - int err = -ENOMEM; - pte_t *pte; - pte_t pte_val; - spinlock_t *ptl; - - pte = get_locked_pte(mm, addr, &ptl); - if (!pte) - goto out; - - /* - * This page may have been truncated. Tell the - * caller about it. - */ - err = -EINVAL; - inode = vma->vm_file->f_mapping->host; - size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - if (!page->mapping || page->index >= size) - goto unlock; - err = -ENOMEM; - if (page_mapcount(page) > INT_MAX/2) - goto unlock; - - if (pte_none(*pte) || !zap_pte(mm, vma, addr, pte)) - inc_mm_counter(mm, file_rss); - - flush_icache_page(vma, page); - pte_val = mk_pte(page, prot); - set_pte_at(mm, addr, pte, pte_val); - page_add_file_rmap(page); - update_mmu_cache(vma, addr, pte_val); - lazy_mmu_prot_update(pte_val); - err = 0; -unlock: - pte_unmap_unlock(pte, ptl); -out: - return err; -} -EXPORT_SYMBOL(install_page); - -/* * Install a file pte to a given virtual memory address, release any * previously existing mapping. */ -int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, +static int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot) { int err = -ENOMEM; @@ -210,8 +162,7 @@ asmlinkage long sys_remap_file_pages(uns if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR)) goto out; - if ((!vma->vm_ops || !vma->vm_ops->populate) && - !(vma->vm_flags & VM_CAN_NONLINEAR)) + if (!vma->vm_flags & VM_CAN_NONLINEAR) goto out; if (end <= start || start < vma->vm_start || end > vma->vm_end) @@ -241,18 +192,14 @@ asmlinkage long sys_remap_file_pages(uns spin_unlock(&mapping->i_mmap_lock); } - if (vma->vm_flags & VM_CAN_NONLINEAR) { - err = populate_range(mm, vma, start, size, pgoff); - if (!err && !(flags & MAP_NONBLOCK)) { - if (unlikely(has_write_lock)) { - downgrade_write(&mm->mmap_sem); - has_write_lock = 0; - } - make_pages_present(start, start+size); + err = populate_range(mm, vma, start, size, pgoff); + if (!err && !(flags & MAP_NONBLOCK)) { + if (unlikely(has_write_lock)) { + downgrade_write(&mm->mmap_sem); + has_write_lock = 0; } - } else - err = vma->vm_ops->populate(vma, start, size, vma->vm_page_prot, - pgoff, flags & MAP_NONBLOCK); + make_pages_present(start, start+size); + } /* * We can't clear VM_NONLINEAR because we'd have to do Index: linux-2.6/mm/memory.c =================================================================== --- linux-2.6.orig/mm/memory.c +++ linux-2.6/mm/memory.c @@ -2327,18 +2327,10 @@ static int do_linear_fault(struct mm_str - vma->vm_start) >> PAGE_CACHE_SHIFT) + vma->vm_pgoff; unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); - return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte); + return __do_fault(mm, vma, address, page_table, pmd, pgoff, + flags, orig_pte); } -static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long address, pte_t *page_table, pmd_t *pmd, - int write_access, pgoff_t pgoff, pte_t orig_pte) -{ - unsigned int flags = FAULT_FLAG_NONLINEAR | - (write_access ? FAULT_FLAG_WRITE : 0); - - return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte); -} /* * Fault of a previously existing named mapping. Repopulate the pte @@ -2349,17 +2341,19 @@ static int do_nonlinear_fault(struct mm_ * but allow concurrent faults), and pte mapped but not yet locked. * We return with mmap_sem still held, but pte unmapped and unlocked. */ -static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, +static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *page_table, pmd_t *pmd, int write_access, pte_t orig_pte) { + unsigned int flags = FAULT_FLAG_NONLINEAR | + (write_access ? FAULT_FLAG_WRITE : 0); pgoff_t pgoff; - int err; if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) return VM_FAULT_MINOR; - if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { + if (unlikely(!(vma->vm_flags & VM_NONLINEAR) || + !(vma->vm_flags & VM_CAN_NONLINEAR))) { /* * Page table corrupted: show pte and kill process. */ @@ -2369,18 +2363,8 @@ static int do_file_page(struct mm_struct pgoff = pte_to_pgoff(orig_pte); - if (vma->vm_ops && vma->vm_ops->fault) - return do_nonlinear_fault(mm, vma, address, page_table, pmd, - write_access, pgoff, orig_pte); - - /* We can then assume vm->vm_ops && vma->vm_ops->populate */ - err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, - vma->vm_page_prot, pgoff, 0); - if (err == -ENOMEM) - return VM_FAULT_OOM; - if (err) - return VM_FAULT_SIGBUS; - return VM_FAULT_MAJOR; + return __do_fault(mm, vma, address, page_table, pmd, pgoff, + flags, orig_pte); } /* @@ -2416,7 +2400,7 @@ static inline int handle_pte_fault(struc pte, pmd, write_access); } if (pte_file(entry)) - return do_file_page(mm, vma, address, + return do_nonlinear_fault(mm, vma, address, pte, pmd, write_access, entry); return do_swap_page(mm, vma, address, pte, pmd, write_access, entry); Index: linux-2.6/Documentation/feature-removal-schedule.txt =================================================================== --- linux-2.6.orig/Documentation/feature-removal-schedule.txt +++ linux-2.6/Documentation/feature-removal-schedule.txt @@ -203,26 +203,8 @@ Who: Nick Piggin <npiggin@suse.de> --------------------------- -What: filemap_nopage, filemap_populate -When: February 2007 -Why: These legacy interfaces no longer have any callers in the kernel and - any functionality provided can be provided with filemap_fault. The - removal schedule is short because they are a big maintainence burden - and have some bugs. -Who: Nick Piggin <npiggin@suse.de> - ---------------------------- - -What: vm_ops.populate, install_page -When: February 2007 -Why: These legacy interfaces no longer have any callers in the kernel and - any functionality provided can be provided with vm_ops.fault. -Who: Nick Piggin <npiggin@suse.de> - ---------------------------- - What: vm_ops.nopage -When: October 2008, provided in-kernel callers have been converted +When: October 2007, provided in-kernel callers have been converted Why: This interface is replaced by vm_ops.fault, but it has been around forever, is used by a lot of drivers, and doesn't cost much to maintain. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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