dax,ext2: replace the XIP page fault handler with the DAX page fault handler
Instead of calling aops->get_xip_mem from the fault handler, the filesystem passes a get_block_t that is used to find the appropriate blocks. This requires that all architectures implement copy_user_page(). At the time of writing, mips and arm do not. Patches exist and are in progress. [akpm@linux-foundation.org: remap_file_pages went away] Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Andreas Dilger <andreas.dilger@intel.com> Cc: Boaz Harrosh <boaz@plexistor.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox
committed by
Linus Torvalds
Linus Torvalds
parent
289c6aedac
commit
f7ca90b160
206
mm/filemap_xip.c
206
mm/filemap_xip.c
@@ -22,212 +22,6 @@
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#include <asm/tlbflush.h>
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#include <asm/io.h>
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/*
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* We do use our own empty page to avoid interference with other users
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* of ZERO_PAGE(), such as /dev/zero
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*/
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static DEFINE_MUTEX(xip_sparse_mutex);
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static seqcount_t xip_sparse_seq = SEQCNT_ZERO(xip_sparse_seq);
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static struct page *__xip_sparse_page;
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/* called under xip_sparse_mutex */
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static struct page *xip_sparse_page(void)
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{
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if (!__xip_sparse_page) {
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struct page *page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
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if (page)
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__xip_sparse_page = page;
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}
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return __xip_sparse_page;
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}
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/*
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* __xip_unmap is invoked from xip_unmap and xip_write
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*
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* This function walks all vmas of the address_space and unmaps the
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* __xip_sparse_page when found at pgoff.
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*/
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static void __xip_unmap(struct address_space * mapping, unsigned long pgoff)
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{
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struct vm_area_struct *vma;
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struct page *page;
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unsigned count;
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int locked = 0;
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count = read_seqcount_begin(&xip_sparse_seq);
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page = __xip_sparse_page;
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if (!page)
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return;
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retry:
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i_mmap_lock_read(mapping);
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vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
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pte_t *pte, pteval;
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spinlock_t *ptl;
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struct mm_struct *mm = vma->vm_mm;
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unsigned long address = vma->vm_start +
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((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
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BUG_ON(address < vma->vm_start || address >= vma->vm_end);
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pte = page_check_address(page, mm, address, &ptl, 1);
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if (pte) {
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/* Nuke the page table entry. */
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flush_cache_page(vma, address, pte_pfn(*pte));
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pteval = ptep_clear_flush(vma, address, pte);
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page_remove_rmap(page);
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dec_mm_counter(mm, MM_FILEPAGES);
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BUG_ON(pte_dirty(pteval));
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pte_unmap_unlock(pte, ptl);
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/* must invalidate_page _before_ freeing the page */
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mmu_notifier_invalidate_page(mm, address);
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page_cache_release(page);
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}
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}
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i_mmap_unlock_read(mapping);
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if (locked) {
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mutex_unlock(&xip_sparse_mutex);
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} else if (read_seqcount_retry(&xip_sparse_seq, count)) {
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mutex_lock(&xip_sparse_mutex);
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locked = 1;
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goto retry;
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}
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}
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/*
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* xip_fault() is invoked via the vma operations vector for a
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* mapped memory region to read in file data during a page fault.
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*
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* This function is derived from filemap_fault, but used for execute in place
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*/
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static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct file *file = vma->vm_file;
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struct address_space *mapping = file->f_mapping;
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struct inode *inode = mapping->host;
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pgoff_t size;
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void *xip_mem;
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unsigned long xip_pfn;
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struct page *page;
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int error;
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/* XXX: are VM_FAULT_ codes OK? */
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again:
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size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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if (vmf->pgoff >= size)
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return VM_FAULT_SIGBUS;
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error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0,
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&xip_mem, &xip_pfn);
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if (likely(!error))
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goto found;
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if (error != -ENODATA)
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return VM_FAULT_OOM;
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/* sparse block */
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if ((vma->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
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(vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) &&
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(!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
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int err;
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/* maybe shared writable, allocate new block */
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mutex_lock(&xip_sparse_mutex);
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error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 1,
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&xip_mem, &xip_pfn);
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mutex_unlock(&xip_sparse_mutex);
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if (error)
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return VM_FAULT_SIGBUS;
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/* unmap sparse mappings at pgoff from all other vmas */
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__xip_unmap(mapping, vmf->pgoff);
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found:
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/*
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* We must recheck i_size under i_mmap_rwsem to prevent races
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* with truncation
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*/
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i_mmap_lock_read(mapping);
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size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
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PAGE_CACHE_SHIFT;
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if (unlikely(vmf->pgoff >= size)) {
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i_mmap_unlock_read(mapping);
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return VM_FAULT_SIGBUS;
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}
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err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
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xip_pfn);
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i_mmap_unlock_read(mapping);
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if (err == -ENOMEM)
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return VM_FAULT_OOM;
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/*
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* err == -EBUSY is fine, we've raced against another thread
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* that faulted-in the same page
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*/
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if (err != -EBUSY)
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BUG_ON(err);
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return VM_FAULT_NOPAGE;
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} else {
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int err, ret = VM_FAULT_OOM;
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mutex_lock(&xip_sparse_mutex);
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write_seqcount_begin(&xip_sparse_seq);
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error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0,
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&xip_mem, &xip_pfn);
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if (unlikely(!error)) {
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write_seqcount_end(&xip_sparse_seq);
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mutex_unlock(&xip_sparse_mutex);
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goto again;
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}
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if (error != -ENODATA)
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goto out;
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/*
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* We must recheck i_size under i_mmap_rwsem to prevent races
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* with truncation
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*/
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i_mmap_lock_read(mapping);
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size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
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PAGE_CACHE_SHIFT;
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if (unlikely(vmf->pgoff >= size)) {
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ret = VM_FAULT_SIGBUS;
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goto unlock;
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}
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/* not shared and writable, use xip_sparse_page() */
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page = xip_sparse_page();
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if (!page)
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goto unlock;
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err = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
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page);
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if (err == -ENOMEM)
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goto unlock;
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ret = VM_FAULT_NOPAGE;
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unlock:
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i_mmap_unlock_read(mapping);
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out:
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write_seqcount_end(&xip_sparse_seq);
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mutex_unlock(&xip_sparse_mutex);
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return ret;
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}
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}
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static const struct vm_operations_struct xip_file_vm_ops = {
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.fault = xip_file_fault,
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.page_mkwrite = filemap_page_mkwrite,
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};
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int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
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{
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BUG_ON(!file->f_mapping->a_ops->get_xip_mem);
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file_accessed(file);
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vma->vm_ops = &xip_file_vm_ops;
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vma->vm_flags |= VM_MIXEDMAP;
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return 0;
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}
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EXPORT_SYMBOL_GPL(xip_file_mmap);
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/*
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* truncate a page used for execute in place
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* functionality is analog to block_truncate_page but does use get_xip_mem
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