![Linus Torvalds](/assets/img/avatar_default.png)
Pull more vfs updates from Al Viro: "Assorted VFS fixes and related cleanups (IMO the most interesting in that part are f_path-related things and Eric's descriptor-related stuff). UFS regression fixes (it got broken last cycle). 9P fixes. fs-cache series, DAX patches, Jan's file_remove_suid() work" [ I'd say this is much more than "fixes and related cleanups". The file_table locking rule change by Eric Dumazet is a rather big and fundamental update even if the patch isn't huge. - Linus ] * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits) 9p: cope with bogus responses from server in p9_client_{read,write} p9_client_write(): avoid double p9_free_req() 9p: forgetting to cancel request on interrupted zero-copy RPC dax: bdev_direct_access() may sleep block: Add support for DAX reads/writes to block devices dax: Use copy_from_iter_nocache dax: Add block size note to documentation fs/file.c: __fget() and dup2() atomicity rules fs/file.c: don't acquire files->file_lock in fd_install() fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation vfs: avoid creation of inode number 0 in get_next_ino namei: make set_root_rcu() return void make simple_positive() public ufs: use dir_pages instead of ufs_dir_pages() pagemap.h: move dir_pages() over there remove the pointless include of lglock.h fs: cleanup slight list_entry abuse xfs: Correctly lock inode when removing suid and file capabilities fs: Call security_ops->inode_killpriv on truncate fs: Provide function telling whether file_remove_privs() will do anything ...
573 lines
16 KiB
C
573 lines
16 KiB
C
/*
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* fs/dax.c - Direct Access filesystem code
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* Copyright (c) 2013-2014 Intel Corporation
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* Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
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* Author: Ross Zwisler <ross.zwisler@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/atomic.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/fs.h>
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#include <linux/genhd.h>
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#include <linux/highmem.h>
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#include <linux/memcontrol.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/sched.h>
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#include <linux/uio.h>
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#include <linux/vmstat.h>
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int dax_clear_blocks(struct inode *inode, sector_t block, long size)
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{
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struct block_device *bdev = inode->i_sb->s_bdev;
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sector_t sector = block << (inode->i_blkbits - 9);
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might_sleep();
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do {
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void *addr;
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unsigned long pfn;
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long count;
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count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
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if (count < 0)
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return count;
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BUG_ON(size < count);
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while (count > 0) {
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unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
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if (pgsz > count)
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pgsz = count;
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if (pgsz < PAGE_SIZE)
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memset(addr, 0, pgsz);
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else
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clear_page(addr);
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addr += pgsz;
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size -= pgsz;
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count -= pgsz;
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BUG_ON(pgsz & 511);
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sector += pgsz / 512;
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cond_resched();
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}
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} while (size);
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return 0;
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}
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EXPORT_SYMBOL_GPL(dax_clear_blocks);
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static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
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{
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unsigned long pfn;
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sector_t sector = bh->b_blocknr << (blkbits - 9);
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return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
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}
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static void dax_new_buf(void *addr, unsigned size, unsigned first, loff_t pos,
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loff_t end)
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{
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loff_t final = end - pos + first; /* The final byte of the buffer */
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if (first > 0)
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memset(addr, 0, first);
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if (final < size)
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memset(addr + final, 0, size - final);
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}
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static bool buffer_written(struct buffer_head *bh)
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{
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return buffer_mapped(bh) && !buffer_unwritten(bh);
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}
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/*
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* When ext4 encounters a hole, it returns without modifying the buffer_head
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* which means that we can't trust b_size. To cope with this, we set b_state
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* to 0 before calling get_block and, if any bit is set, we know we can trust
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* b_size. Unfortunate, really, since ext4 knows precisely how long a hole is
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* and would save us time calling get_block repeatedly.
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*/
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static bool buffer_size_valid(struct buffer_head *bh)
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{
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return bh->b_state != 0;
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}
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static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
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loff_t start, loff_t end, get_block_t get_block,
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struct buffer_head *bh)
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{
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ssize_t retval = 0;
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loff_t pos = start;
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loff_t max = start;
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loff_t bh_max = start;
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void *addr;
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bool hole = false;
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if (iov_iter_rw(iter) != WRITE)
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end = min(end, i_size_read(inode));
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while (pos < end) {
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unsigned len;
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if (pos == max) {
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unsigned blkbits = inode->i_blkbits;
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sector_t block = pos >> blkbits;
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unsigned first = pos - (block << blkbits);
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long size;
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if (pos == bh_max) {
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bh->b_size = PAGE_ALIGN(end - pos);
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bh->b_state = 0;
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retval = get_block(inode, block, bh,
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iov_iter_rw(iter) == WRITE);
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if (retval)
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break;
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if (!buffer_size_valid(bh))
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bh->b_size = 1 << blkbits;
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bh_max = pos - first + bh->b_size;
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} else {
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unsigned done = bh->b_size -
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(bh_max - (pos - first));
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bh->b_blocknr += done >> blkbits;
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bh->b_size -= done;
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}
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hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
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if (hole) {
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addr = NULL;
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size = bh->b_size - first;
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} else {
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retval = dax_get_addr(bh, &addr, blkbits);
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if (retval < 0)
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break;
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if (buffer_unwritten(bh) || buffer_new(bh))
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dax_new_buf(addr, retval, first, pos,
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end);
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addr += first;
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size = retval - first;
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}
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max = min(pos + size, end);
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}
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if (iov_iter_rw(iter) == WRITE)
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len = copy_from_iter_nocache(addr, max - pos, iter);
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else if (!hole)
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len = copy_to_iter(addr, max - pos, iter);
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else
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len = iov_iter_zero(max - pos, iter);
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if (!len)
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break;
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pos += len;
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addr += len;
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}
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return (pos == start) ? retval : pos - start;
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}
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/**
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* dax_do_io - Perform I/O to a DAX file
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* @iocb: The control block for this I/O
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* @inode: The file which the I/O is directed at
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* @iter: The addresses to do I/O from or to
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* @pos: The file offset where the I/O starts
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* @get_block: The filesystem method used to translate file offsets to blocks
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* @end_io: A filesystem callback for I/O completion
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* @flags: See below
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*
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* This function uses the same locking scheme as do_blockdev_direct_IO:
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* If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the
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* caller for writes. For reads, we take and release the i_mutex ourselves.
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* If DIO_LOCKING is not set, the filesystem takes care of its own locking.
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* As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O
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* is in progress.
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*/
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ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
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struct iov_iter *iter, loff_t pos, get_block_t get_block,
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dio_iodone_t end_io, int flags)
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{
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struct buffer_head bh;
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ssize_t retval = -EINVAL;
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loff_t end = pos + iov_iter_count(iter);
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memset(&bh, 0, sizeof(bh));
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if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) {
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struct address_space *mapping = inode->i_mapping;
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mutex_lock(&inode->i_mutex);
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retval = filemap_write_and_wait_range(mapping, pos, end - 1);
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if (retval) {
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mutex_unlock(&inode->i_mutex);
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goto out;
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}
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}
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/* Protects against truncate */
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if (!(flags & DIO_SKIP_DIO_COUNT))
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inode_dio_begin(inode);
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retval = dax_io(inode, iter, pos, end, get_block, &bh);
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if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ)
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mutex_unlock(&inode->i_mutex);
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if ((retval > 0) && end_io)
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end_io(iocb, pos, retval, bh.b_private);
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if (!(flags & DIO_SKIP_DIO_COUNT))
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inode_dio_end(inode);
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out:
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return retval;
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}
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EXPORT_SYMBOL_GPL(dax_do_io);
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/*
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* The user has performed a load from a hole in the file. Allocating
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* a new page in the file would cause excessive storage usage for
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* workloads with sparse files. We allocate a page cache page instead.
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* We'll kick it out of the page cache if it's ever written to,
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* otherwise it will simply fall out of the page cache under memory
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* pressure without ever having been dirtied.
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*/
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static int dax_load_hole(struct address_space *mapping, struct page *page,
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struct vm_fault *vmf)
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{
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unsigned long size;
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struct inode *inode = mapping->host;
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if (!page)
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page = find_or_create_page(mapping, vmf->pgoff,
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GFP_KERNEL | __GFP_ZERO);
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if (!page)
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return VM_FAULT_OOM;
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/* Recheck i_size under page lock to avoid truncate race */
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (vmf->pgoff >= size) {
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unlock_page(page);
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page_cache_release(page);
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return VM_FAULT_SIGBUS;
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}
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vmf->page = page;
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return VM_FAULT_LOCKED;
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}
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static int copy_user_bh(struct page *to, struct buffer_head *bh,
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unsigned blkbits, unsigned long vaddr)
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{
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void *vfrom, *vto;
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if (dax_get_addr(bh, &vfrom, blkbits) < 0)
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return -EIO;
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vto = kmap_atomic(to);
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copy_user_page(vto, vfrom, vaddr, to);
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kunmap_atomic(vto);
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return 0;
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}
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static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
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struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct address_space *mapping = inode->i_mapping;
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sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
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unsigned long vaddr = (unsigned long)vmf->virtual_address;
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void *addr;
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unsigned long pfn;
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pgoff_t size;
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int error;
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i_mmap_lock_read(mapping);
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/*
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* Check truncate didn't happen while we were allocating a block.
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* If it did, this block may or may not be still allocated to the
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* file. We can't tell the filesystem to free it because we can't
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* take i_mutex here. In the worst case, the file still has blocks
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* allocated past the end of the file.
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*/
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (unlikely(vmf->pgoff >= size)) {
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error = -EIO;
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goto out;
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}
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error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
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if (error < 0)
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goto out;
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if (error < PAGE_SIZE) {
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error = -EIO;
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goto out;
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}
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if (buffer_unwritten(bh) || buffer_new(bh))
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clear_page(addr);
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error = vm_insert_mixed(vma, vaddr, pfn);
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out:
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i_mmap_unlock_read(mapping);
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return error;
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}
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/**
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* __dax_fault - handle a page fault on a DAX file
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* @vma: The virtual memory area where the fault occurred
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* @vmf: The description of the fault
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* @get_block: The filesystem method used to translate file offsets to blocks
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*
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* When a page fault occurs, filesystems may call this helper in their
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* fault handler for DAX files. __dax_fault() assumes the caller has done all
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* the necessary locking for the page fault to proceed successfully.
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*/
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int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
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get_block_t get_block, dax_iodone_t complete_unwritten)
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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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struct page *page;
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struct buffer_head bh;
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unsigned long vaddr = (unsigned long)vmf->virtual_address;
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unsigned blkbits = inode->i_blkbits;
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sector_t block;
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pgoff_t size;
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int error;
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int major = 0;
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (vmf->pgoff >= size)
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return VM_FAULT_SIGBUS;
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memset(&bh, 0, sizeof(bh));
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block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits);
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bh.b_size = PAGE_SIZE;
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repeat:
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page = find_get_page(mapping, vmf->pgoff);
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if (page) {
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if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
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page_cache_release(page);
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return VM_FAULT_RETRY;
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}
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if (unlikely(page->mapping != mapping)) {
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unlock_page(page);
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page_cache_release(page);
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goto repeat;
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}
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (unlikely(vmf->pgoff >= size)) {
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/*
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* We have a struct page covering a hole in the file
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* from a read fault and we've raced with a truncate
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*/
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error = -EIO;
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goto unlock_page;
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}
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}
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error = get_block(inode, block, &bh, 0);
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if (!error && (bh.b_size < PAGE_SIZE))
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error = -EIO; /* fs corruption? */
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if (error)
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goto unlock_page;
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if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
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if (vmf->flags & FAULT_FLAG_WRITE) {
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error = get_block(inode, block, &bh, 1);
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count_vm_event(PGMAJFAULT);
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mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
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major = VM_FAULT_MAJOR;
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if (!error && (bh.b_size < PAGE_SIZE))
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error = -EIO;
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if (error)
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goto unlock_page;
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} else {
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return dax_load_hole(mapping, page, vmf);
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}
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}
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if (vmf->cow_page) {
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struct page *new_page = vmf->cow_page;
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if (buffer_written(&bh))
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error = copy_user_bh(new_page, &bh, blkbits, vaddr);
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else
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clear_user_highpage(new_page, vaddr);
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if (error)
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goto unlock_page;
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vmf->page = page;
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if (!page) {
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i_mmap_lock_read(mapping);
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/* Check we didn't race with truncate */
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size = (i_size_read(inode) + PAGE_SIZE - 1) >>
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PAGE_SHIFT;
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if (vmf->pgoff >= size) {
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i_mmap_unlock_read(mapping);
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error = -EIO;
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goto out;
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}
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}
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return VM_FAULT_LOCKED;
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}
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/* Check we didn't race with a read fault installing a new page */
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if (!page && major)
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page = find_lock_page(mapping, vmf->pgoff);
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if (page) {
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unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
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PAGE_CACHE_SIZE, 0);
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delete_from_page_cache(page);
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unlock_page(page);
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page_cache_release(page);
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}
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/*
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* If we successfully insert the new mapping over an unwritten extent,
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* we need to ensure we convert the unwritten extent. If there is an
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* error inserting the mapping, the filesystem needs to leave it as
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* unwritten to prevent exposure of the stale underlying data to
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* userspace, but we still need to call the completion function so
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* the private resources on the mapping buffer can be released. We
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* indicate what the callback should do via the uptodate variable, same
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* as for normal BH based IO completions.
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*/
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error = dax_insert_mapping(inode, &bh, vma, vmf);
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if (buffer_unwritten(&bh))
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complete_unwritten(&bh, !error);
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out:
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if (error == -ENOMEM)
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return VM_FAULT_OOM | major;
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/* -EBUSY is fine, somebody else faulted on the same PTE */
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if ((error < 0) && (error != -EBUSY))
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return VM_FAULT_SIGBUS | major;
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return VM_FAULT_NOPAGE | major;
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unlock_page:
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if (page) {
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unlock_page(page);
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page_cache_release(page);
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}
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goto out;
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}
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EXPORT_SYMBOL(__dax_fault);
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/**
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* dax_fault - handle a page fault on a DAX file
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* @vma: The virtual memory area where the fault occurred
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* @vmf: The description of the fault
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* @get_block: The filesystem method used to translate file offsets to blocks
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*
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* When a page fault occurs, filesystems may call this helper in their
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* fault handler for DAX files.
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*/
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int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
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get_block_t get_block, dax_iodone_t complete_unwritten)
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{
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int result;
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struct super_block *sb = file_inode(vma->vm_file)->i_sb;
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if (vmf->flags & FAULT_FLAG_WRITE) {
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sb_start_pagefault(sb);
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file_update_time(vma->vm_file);
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}
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result = __dax_fault(vma, vmf, get_block, complete_unwritten);
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if (vmf->flags & FAULT_FLAG_WRITE)
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sb_end_pagefault(sb);
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return result;
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}
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EXPORT_SYMBOL_GPL(dax_fault);
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/**
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* dax_pfn_mkwrite - handle first write to DAX page
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* @vma: The virtual memory area where the fault occurred
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* @vmf: The description of the fault
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*
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*/
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int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct super_block *sb = file_inode(vma->vm_file)->i_sb;
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sb_start_pagefault(sb);
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file_update_time(vma->vm_file);
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sb_end_pagefault(sb);
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return VM_FAULT_NOPAGE;
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}
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EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
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/**
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* dax_zero_page_range - zero a range within a page of a DAX file
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* @inode: The file being truncated
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* @from: The file offset that is being truncated to
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* @length: The number of bytes to zero
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* @get_block: The filesystem method used to translate file offsets to blocks
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*
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* This function can be called by a filesystem when it is zeroing part of a
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* page in a DAX file. This is intended for hole-punch operations. If
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* you are truncating a file, the helper function dax_truncate_page() may be
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* more convenient.
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*
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* We work in terms of PAGE_CACHE_SIZE here for commonality with
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* block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
|
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* took care of disposing of the unnecessary blocks. Even if the filesystem
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* block size is smaller than PAGE_SIZE, we have to zero the rest of the page
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* since the file might be mmapped.
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*/
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int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
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get_block_t get_block)
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{
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struct buffer_head bh;
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pgoff_t index = from >> PAGE_CACHE_SHIFT;
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unsigned offset = from & (PAGE_CACHE_SIZE-1);
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int err;
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/* Block boundary? Nothing to do */
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if (!length)
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return 0;
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BUG_ON((offset + length) > PAGE_CACHE_SIZE);
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|
|
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memset(&bh, 0, sizeof(bh));
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bh.b_size = PAGE_CACHE_SIZE;
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err = get_block(inode, index, &bh, 0);
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if (err < 0)
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return err;
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if (buffer_written(&bh)) {
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void *addr;
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err = dax_get_addr(&bh, &addr, inode->i_blkbits);
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if (err < 0)
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return err;
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memset(addr + offset, 0, length);
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|
}
|
|
|
|
return 0;
|
|
}
|
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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);
|