Merge branch 'akpm' (patches from Andrew)

Merge fifth set of updates from Andrew Morton:

 - A few things which were awaiting merges from linux-next:
     - rtc
     - ocfs2
     - misc others

 - Willy's "dax" feature: direct fs access to memory (mainly NV-DIMMs)
   which isn't backed by pageframes.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (37 commits)
  rtc: add driver for DS1685 family of real time clocks
  MAINTAINERS: add entry for Maxim PMICs on Samsung boards
  lib/Kconfig: use bool instead of boolean
  powerpc: drop _PAGE_FILE and pte_file()-related helpers
  ocfs2: set append dio as a ro compat feature
  ocfs2: wait for orphan recovery first once append O_DIRECT write crash
  ocfs2: complete the rest request through buffer io
  ocfs2: do not fallback to buffer I/O write if appending
  ocfs2: allocate blocks in ocfs2_direct_IO_get_blocks
  ocfs2: implement ocfs2_direct_IO_write
  ocfs2: add orphan recovery types in ocfs2_recover_orphans
  ocfs2: add functions to add and remove inode in orphan dir
  ocfs2: prepare some interfaces used in append direct io
  MAINTAINERS: fix spelling mistake & remove trailing WS
  dax: does not work correctly with virtual aliasing caches
  brd: rename XIP to DAX
  ext4: add DAX functionality
  dax: add dax_zero_page_range
  ext2: get rid of most mentions of XIP in ext2
  ext2: remove ext2_aops_xip
  ...

1 files changed, 534 insertions, 0 deletions

diff --git a/fs/dax.c b/fs/dax.c
new file mode 100644
index 000000000000..ed1619ec6537
--- /dev/null
+++ b/fs/dax.c
@@ -0,0 +1,534 @@
+/*
+ * fs/dax.c - Direct Access filesystem code
+ * Copyright (c) 2013-2014 Intel Corporation
+ * Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
+ * Author: Ross Zwisler <ross.zwisler@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/atomic.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/highmem.h>
+#include <linux/memcontrol.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/uio.h>
+#include <linux/vmstat.h>
+
+int dax_clear_blocks(struct inode *inode, sector_t block, long size)
+{
+        struct block_device *bdev = inode->i_sb->s_bdev;
+        sector_t sector = block << (inode->i_blkbits - 9);
+
+        might_sleep();
+        do {
+                void *addr;
+                unsigned long pfn;
+                long count;
+
+                count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
+                if (count < 0)
+                        return count;
+                BUG_ON(size < count);
+                while (count > 0) {
+                        unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
+                        if (pgsz > count)
+                                pgsz = count;
+                        if (pgsz < PAGE_SIZE)
+                                memset(addr, 0, pgsz);
+                        else
+                                clear_page(addr);
+                        addr += pgsz;
+                        size -= pgsz;
+                        count -= pgsz;
+                        BUG_ON(pgsz & 511);
+                        sector += pgsz / 512;
+                        cond_resched();
+                }
+        } while (size);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(dax_clear_blocks);
+
+static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
+{
+        unsigned long pfn;
+        sector_t sector = bh->b_blocknr << (blkbits - 9);
+        return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
+}
+
+static void dax_new_buf(void *addr, unsigned size, unsigned first, loff_t pos,
+                        loff_t end)
+{
+        loff_t final = end - pos + first; /* The final byte of the buffer */
+
+        if (first > 0)
+                memset(addr, 0, first);
+        if (final < size)
+                memset(addr + final, 0, size - final);
+}
+
+static bool buffer_written(struct buffer_head *bh)
+{
+        return buffer_mapped(bh) && !buffer_unwritten(bh);
+}
+
+/*
+ * When ext4 encounters a hole, it returns without modifying the buffer_head
+ * which means that we can't trust b_size.  To cope with this, we set b_state
+ * to 0 before calling get_block and, if any bit is set, we know we can trust
+ * b_size.  Unfortunate, really, since ext4 knows precisely how long a hole is
+ * and would save us time calling get_block repeatedly.
+ */
+static bool buffer_size_valid(struct buffer_head *bh)
+{
+        return bh->b_state != 0;
+}
+
+static ssize_t dax_io(int rw, struct inode *inode, struct iov_iter *iter,
+                        loff_t start, loff_t end, get_block_t get_block,
+                        struct buffer_head *bh)
+{
+        ssize_t retval = 0;
+        loff_t pos = start;
+        loff_t max = start;
+        loff_t bh_max = start;
+        void *addr;
+        bool hole = false;
+
+        if (rw != WRITE)
+                end = min(end, i_size_read(inode));
+
+        while (pos < end) {
+                unsigned len;
+                if (pos == max) {
+                        unsigned blkbits = inode->i_blkbits;
+                        sector_t block = pos >> blkbits;
+                        unsigned first = pos - (block << blkbits);
+                        long size;
+
+                        if (pos == bh_max) {
+                                bh->b_size = PAGE_ALIGN(end - pos);
+                                bh->b_state = 0;
+                                retval = get_block(inode, block, bh,
+                                                                rw == WRITE);
+                                if (retval)
+                                        break;
+                                if (!buffer_size_valid(bh))
+                                        bh->b_size = 1 << blkbits;
+                                bh_max = pos - first + bh->b_size;
+                        } else {
+                                unsigned done = bh->b_size -
+                                                (bh_max - (pos - first));
+                                bh->b_blocknr += done >> blkbits;
+                                bh->b_size -= done;
+                        }
+
+                        hole = (rw != WRITE) && !buffer_written(bh);
+                        if (hole) {
+                                addr = NULL;
+                                size = bh->b_size - first;
+                        } else {
+                                retval = dax_get_addr(bh, &addr, blkbits);
+                                if (retval < 0)
+                                        break;
+                                if (buffer_unwritten(bh) || buffer_new(bh))
+                                        dax_new_buf(addr, retval, first, pos,
+                                                                        end);
+                                addr += first;
+                                size = retval - first;
+                        }
+                        max = min(pos + size, end);
+                }
+
+                if (rw == WRITE)
+                        len = copy_from_iter(addr, max - pos, iter);
+                else if (!hole)
+                        len = copy_to_iter(addr, max - pos, iter);
+                else
+                        len = iov_iter_zero(max - pos, iter);
+
+                if (!len)
+                        break;
+
+                pos += len;
+                addr += len;
+        }
+
+        return (pos == start) ? retval : pos - start;
+}
+
+/**
+ * dax_do_io - Perform I/O to a DAX file
+ * @rw: READ to read or WRITE to write
+ * @iocb: The control block for this I/O
+ * @inode: The file which the I/O is directed at
+ * @iter: The addresses to do I/O from or to
+ * @pos: The file offset where the I/O starts
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ * @end_io: A filesystem callback for I/O completion
+ * @flags: See below
+ *
+ * This function uses the same locking scheme as do_blockdev_direct_IO:
+ * If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the
+ * caller for writes.  For reads, we take and release the i_mutex ourselves.
+ * If DIO_LOCKING is not set, the filesystem takes care of its own locking.
+ * As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O
+ * is in progress.
+ */
+ssize_t dax_do_io(int rw, struct kiocb *iocb, struct inode *inode,
+                        struct iov_iter *iter, loff_t pos,
+                        get_block_t get_block, dio_iodone_t end_io, int flags)
+{
+        struct buffer_head bh;
+        ssize_t retval = -EINVAL;
+        loff_t end = pos + iov_iter_count(iter);
+
+        memset(&bh, 0, sizeof(bh));
+
+        if ((flags & DIO_LOCKING) && (rw == READ)) {
+                struct address_space *mapping = inode->i_mapping;
+                mutex_lock(&inode->i_mutex);
+                retval = filemap_write_and_wait_range(mapping, pos, end - 1);
+                if (retval) {
+                        mutex_unlock(&inode->i_mutex);
+                        goto out;
+                }
+        }
+
+        /* Protects against truncate */
+        atomic_inc(&inode->i_dio_count);
+
+        retval = dax_io(rw, inode, iter, pos, end, get_block, &bh);
+
+        if ((flags & DIO_LOCKING) && (rw == READ))
+                mutex_unlock(&inode->i_mutex);
+
+        if ((retval > 0) && end_io)
+                end_io(iocb, pos, retval, bh.b_private);
+
+        inode_dio_done(inode);
+ out:
+        return retval;
+}
+EXPORT_SYMBOL_GPL(dax_do_io);
+
+/*
+ * The user has performed a load from a hole in the file.  Allocating
+ * a new page in the file would cause excessive storage usage for
+ * workloads with sparse files.  We allocate a page cache page instead.
+ * We'll kick it out of the page cache if it's ever written to,
+ * otherwise it will simply fall out of the page cache under memory
+ * pressure without ever having been dirtied.
+ */
+static int dax_load_hole(struct address_space *mapping, struct page *page,
+                                                        struct vm_fault *vmf)
+{
+        unsigned long size;
+        struct inode *inode = mapping->host;
+        if (!page)
+                page = find_or_create_page(mapping, vmf->pgoff,
+                                                GFP_KERNEL | __GFP_ZERO);
+        if (!page)
+                return VM_FAULT_OOM;
+        /* Recheck i_size under page lock to avoid truncate race */
+        size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        if (vmf->pgoff >= size) {
+                unlock_page(page);
+                page_cache_release(page);
+                return VM_FAULT_SIGBUS;
+        }
+
+        vmf->page = page;
+        return VM_FAULT_LOCKED;
+}
+
+static int copy_user_bh(struct page *to, struct buffer_head *bh,
+                        unsigned blkbits, unsigned long vaddr)
+{
+        void *vfrom, *vto;
+        if (dax_get_addr(bh, &vfrom, blkbits) < 0)
+                return -EIO;
+        vto = kmap_atomic(to);
+        copy_user_page(vto, vfrom, vaddr, to);
+        kunmap_atomic(vto);
+        return 0;
+}
+
+static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
+                        struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+        struct address_space *mapping = inode->i_mapping;
+        sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
+        unsigned long vaddr = (unsigned long)vmf->virtual_address;
+        void *addr;
+        unsigned long pfn;
+        pgoff_t size;
+        int error;
+
+        i_mmap_lock_read(mapping);
+
+        /*
+         * Check truncate didn't happen while we were allocating a block.
+         * If it did, this block may or may not be still allocated to the
+         * file.  We can't tell the filesystem to free it because we can't
+         * take i_mutex here.  In the worst case, the file still has blocks
+         * allocated past the end of the file.
+         */
+        size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        if (unlikely(vmf->pgoff >= size)) {
+                error = -EIO;
+                goto out;
+        }
+
+        error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
+        if (error < 0)
+                goto out;
+        if (error < PAGE_SIZE) {
+                error = -EIO;
+                goto out;
+        }
+
+        if (buffer_unwritten(bh) || buffer_new(bh))
+                clear_page(addr);
+
+        error = vm_insert_mixed(vma, vaddr, pfn);
+
+ out:
+        i_mmap_unlock_read(mapping);
+
+        if (bh->b_end_io)
+                bh->b_end_io(bh, 1);
+
+        return error;
+}
+
+static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
+                        get_block_t get_block)
+{
+        struct file *file = vma->vm_file;
+        struct address_space *mapping = file->f_mapping;
+        struct inode *inode = mapping->host;
+        struct page *page;
+        struct buffer_head bh;
+        unsigned long vaddr = (unsigned long)vmf->virtual_address;
+        unsigned blkbits = inode->i_blkbits;
+        sector_t block;
+        pgoff_t size;
+        int error;
+        int major = 0;
+
+        size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        if (vmf->pgoff >= size)
+                return VM_FAULT_SIGBUS;
+
+        memset(&bh, 0, sizeof(bh));
+        block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits);
+        bh.b_size = PAGE_SIZE;
+
+ repeat:
+        page = find_get_page(mapping, vmf->pgoff);
+        if (page) {
+                if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
+                        page_cache_release(page);
+                        return VM_FAULT_RETRY;
+                }
+                if (unlikely(page->mapping != mapping)) {
+                        unlock_page(page);
+                        page_cache_release(page);
+                        goto repeat;
+                }
+                size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+                if (unlikely(vmf->pgoff >= size)) {
+                        /*
+                         * We have a struct page covering a hole in the file
+                         * from a read fault and we've raced with a truncate
+                         */
+                        error = -EIO;
+                        goto unlock_page;
+                }
+        }
+
+        error = get_block(inode, block, &bh, 0);
+        if (!error && (bh.b_size < PAGE_SIZE))
+                error = -EIO;           /* fs corruption? */
+        if (error)
+                goto unlock_page;
+
+        if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
+                if (vmf->flags & FAULT_FLAG_WRITE) {
+                        error = get_block(inode, block, &bh, 1);
+                        count_vm_event(PGMAJFAULT);
+                        mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+                        major = VM_FAULT_MAJOR;
+                        if (!error && (bh.b_size < PAGE_SIZE))
+                                error = -EIO;
+                        if (error)
+                                goto unlock_page;
+                } else {
+                        return dax_load_hole(mapping, page, vmf);
+                }
+        }
+
+        if (vmf->cow_page) {
+                struct page *new_page = vmf->cow_page;
+                if (buffer_written(&bh))
+                        error = copy_user_bh(new_page, &bh, blkbits, vaddr);
+                else
+                        clear_user_highpage(new_page, vaddr);
+                if (error)
+                        goto unlock_page;
+                vmf->page = page;
+                if (!page) {
+                        i_mmap_lock_read(mapping);
+                        /* Check we didn't race with truncate */
+                        size = (i_size_read(inode) + PAGE_SIZE - 1) >>
+                                                                PAGE_SHIFT;
+                        if (vmf->pgoff >= size) {
+                                i_mmap_unlock_read(mapping);
+                                error = -EIO;
+                                goto out;
+                        }
+                }
+                return VM_FAULT_LOCKED;
+        }
+
+        /* Check we didn't race with a read fault installing a new page */
+        if (!page && major)
+                page = find_lock_page(mapping, vmf->pgoff);
+
+        if (page) {
+                unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
+                                                        PAGE_CACHE_SIZE, 0);
+                delete_from_page_cache(page);
+                unlock_page(page);
+                page_cache_release(page);
+        }
+
+        error = dax_insert_mapping(inode, &bh, vma, vmf);
+
+ out:
+        if (error == -ENOMEM)
+                return VM_FAULT_OOM | major;
+        /* -EBUSY is fine, somebody else faulted on the same PTE */
+        if ((error < 0) && (error != -EBUSY))
+                return VM_FAULT_SIGBUS | major;
+        return VM_FAULT_NOPAGE | major;
+
+ unlock_page:
+        if (page) {
+                unlock_page(page);
+                page_cache_release(page);
+        }
+        goto out;
+}
+
+/**
+ * dax_fault - handle a page fault on a DAX file
+ * @vma: The virtual memory area where the fault occurred
+ * @vmf: The description of the fault
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ *
+ * When a page fault occurs, filesystems may call this helper in their
+ * fault handler for DAX files.
+ */
+int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
+                        get_block_t get_block)
+{
+        int result;
+        struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+
+        if (vmf->flags & FAULT_FLAG_WRITE) {
+                sb_start_pagefault(sb);
+                file_update_time(vma->vm_file);
+        }
+        result = do_dax_fault(vma, vmf, get_block);
+        if (vmf->flags & FAULT_FLAG_WRITE)
+                sb_end_pagefault(sb);
+
+        return result;
+}
+EXPORT_SYMBOL_GPL(dax_fault);
+
+/**
+ * dax_zero_page_range - zero a range within a page of a DAX file
+ * @inode: The file being truncated
+ * @from: The file offset that is being truncated to
+ * @length: The number of bytes to zero
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ *
+ * This function can be called by a filesystem when it is zeroing part of a
+ * page in a DAX file.  This is intended for hole-punch operations.  If
+ * you are truncating a file, the helper function dax_truncate_page() may be
+ * more convenient.
+ *
+ * We work in terms of PAGE_CACHE_SIZE here for commonality with
+ * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
+ * took care of disposing of the unnecessary blocks.  Even if the filesystem
+ * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
+ * since the file might be mmapped.
+ */
+int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
+                                                        get_block_t get_block)
+{
+        struct buffer_head bh;
+        pgoff_t index = from >> PAGE_CACHE_SHIFT;
+        unsigned offset = from & (PAGE_CACHE_SIZE-1);
+        int err;
+
+        /* Block boundary? Nothing to do */
+        if (!length)
+                return 0;
+        BUG_ON((offset + length) > PAGE_CACHE_SIZE);
+
+        memset(&bh, 0, sizeof(bh));
+        bh.b_size = PAGE_CACHE_SIZE;
+        err = get_block(inode, index, &bh, 0);
+        if (err < 0)
+                return err;
+        if (buffer_written(&bh)) {
+                void *addr;
+                err = dax_get_addr(&bh, &addr, inode->i_blkbits);
+                if (err < 0)
+                        return err;
+                memset(addr + offset, 0, length);
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(dax_zero_page_range);
+
+/**
+ * dax_truncate_page - handle a partial page being truncated in a DAX file
+ * @inode: The file being truncated
+ * @from: The file offset that is being truncated to
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ *
+ * Similar to block_truncate_page(), this function can be called by a
+ * filesystem when it is truncating a DAX file to handle the partial page.
+ *
+ * We work in terms of PAGE_CACHE_SIZE here for commonality with
+ * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
+ * took care of disposing of the unnecessary blocks.  Even if the filesystem
+ * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
+ * since the file might be mmapped.
+ */
+int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
+{
+        unsigned length = PAGE_CACHE_ALIGN(from) - from;
+        return dax_zero_page_range(inode, from, length, get_block);
+}
+EXPORT_SYMBOL_GPL(dax_truncate_page);