dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
The DAX implementation needs to protect new calls to ->direct_access() and usage of its return value against the driver for the underlying block device being disabled. Use blk_queue_enter()/blk_queue_exit() to hold off blk_cleanup_queue() from proceeding, or otherwise fail new mapping requests if the request_queue is being torn down. This also introduces blk_dax_ctl to simplify the interface from fs/dax.c through dax_map_atomic() to bdev_direct_access(). [willy@linux.intel.com: fix read() of a hole] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Cc: Jan Kara <jack@suse.com> Cc: Jens Axboe <axboe@fb.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams
Linus Torvalds
Родитель
fe683adabf
Коммит
b2e0d1625e
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@ -455,10 +455,7 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
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/**
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* bdev_direct_access() - Get the address for directly-accessibly memory
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* @bdev: The device containing the memory
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* @sector: The offset within the device
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* @addr: Where to put the address of the memory
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* @pfn: The Page Frame Number for the memory
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* @size: The number of bytes requested
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* @dax: control and output parameters for ->direct_access
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*
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* If a block device is made up of directly addressable memory, this function
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* will tell the caller the PFN and the address of the memory. The address
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@ -469,10 +466,10 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
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* Return: negative errno if an error occurs, otherwise the number of bytes
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* accessible at this address.
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*/
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long bdev_direct_access(struct block_device *bdev, sector_t sector,
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void __pmem **addr, unsigned long *pfn, long size)
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long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
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{
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long avail;
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sector_t sector = dax->sector;
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long avail, size = dax->size;
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const struct block_device_operations *ops = bdev->bd_disk->fops;
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/*
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@ -491,7 +488,7 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
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sector += get_start_sect(bdev);
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if (sector % (PAGE_SIZE / 512))
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return -EINVAL;
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avail = ops->direct_access(bdev, sector, addr, pfn);
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avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn);
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if (!avail)
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return -ERANGE;
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if (avail > 0 && avail & ~PAGE_MASK)
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206
fs/dax.c
206
fs/dax.c
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@ -30,45 +30,65 @@
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#include <linux/vmstat.h>
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#include <linux/sizes.h>
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static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
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{
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struct request_queue *q = bdev->bd_queue;
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long rc = -EIO;
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dax->addr = (void __pmem *) ERR_PTR(-EIO);
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if (blk_queue_enter(q, true) != 0)
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return rc;
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rc = bdev_direct_access(bdev, dax);
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if (rc < 0) {
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dax->addr = (void __pmem *) ERR_PTR(rc);
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blk_queue_exit(q);
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return rc;
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}
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return rc;
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}
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static void dax_unmap_atomic(struct block_device *bdev,
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const struct blk_dax_ctl *dax)
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{
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if (IS_ERR(dax->addr))
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return;
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blk_queue_exit(bdev->bd_queue);
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}
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/*
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* dax_clear_blocks() is called from within transaction context from XFS,
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* and hence this means the stack from this point must follow GFP_NOFS
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* semantics for all operations.
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*/
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int dax_clear_blocks(struct inode *inode, sector_t block, long size)
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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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struct blk_dax_ctl dax = {
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.sector = block << (inode->i_blkbits - 9),
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.size = _size,
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};
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might_sleep();
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do {
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void __pmem *addr;
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unsigned long pfn;
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long count, sz;
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count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
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count = dax_map_atomic(bdev, &dax);
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if (count < 0)
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return count;
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sz = min_t(long, count, SZ_128K);
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clear_pmem(addr, sz);
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size -= sz;
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sector += sz / 512;
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clear_pmem(dax.addr, sz);
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dax.size -= sz;
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dax.sector += sz / 512;
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dax_unmap_atomic(bdev, &dax);
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cond_resched();
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} while (size);
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} while (dax.size);
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wmb_pmem();
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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 __pmem **addr,
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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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/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
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static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
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loff_t pos, loff_t end)
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@ -98,19 +118,29 @@ static bool buffer_size_valid(struct buffer_head *bh)
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return bh->b_state != 0;
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}
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static sector_t to_sector(const struct buffer_head *bh,
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const struct inode *inode)
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{
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sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
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return sector;
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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 __pmem *addr;
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bool hole = false;
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bool need_wmb = false;
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loff_t pos = start, max = start, bh_max = start;
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bool hole = false, need_wmb = false;
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struct block_device *bdev = NULL;
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int rw = iov_iter_rw(iter), rc;
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long map_len = 0;
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struct blk_dax_ctl dax = {
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.addr = (void __pmem *) ERR_PTR(-EIO),
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};
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if (iov_iter_rw(iter) != WRITE)
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if (rw == READ)
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end = min(end, i_size_read(inode));
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while (pos < end) {
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@ -125,13 +155,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
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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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rc = get_block(inode, block, bh, rw == WRITE);
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if (rc)
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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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bdev = bh->b_bdev;
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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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@ -139,47 +169,53 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
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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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hole = rw == READ && !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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dax_unmap_atomic(bdev, &dax);
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dax.sector = to_sector(bh, inode);
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dax.size = bh->b_size;
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map_len = dax_map_atomic(bdev, &dax);
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if (map_len < 0) {
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rc = map_len;
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break;
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}
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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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dax_new_buf(dax.addr, map_len, first,
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pos, end);
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need_wmb = true;
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}
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addr += first;
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size = retval - first;
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dax.addr += first;
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size = map_len - 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_pmem(addr, max - pos, iter);
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len = copy_from_iter_pmem(dax.addr, max - pos, iter);
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need_wmb = true;
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} else if (!hole)
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len = copy_to_iter((void __force *)addr, max - pos,
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len = copy_to_iter((void __force *) dax.addr, max - pos,
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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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retval = -EFAULT;
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rc = -EFAULT;
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break;
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}
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pos += len;
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addr += len;
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if (!IS_ERR(dax.addr))
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dax.addr += len;
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}
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if (need_wmb)
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wmb_pmem();
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dax_unmap_atomic(bdev, &dax);
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return (pos == start) ? retval : pos - start;
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return (pos == start) ? rc : pos - start;
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}
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/**
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@ -268,28 +304,35 @@ static int dax_load_hole(struct address_space *mapping, struct 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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static int copy_user_bh(struct page *to, struct inode *inode,
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struct buffer_head *bh, unsigned long vaddr)
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{
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void __pmem *vfrom;
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struct blk_dax_ctl dax = {
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.sector = to_sector(bh, inode),
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.size = bh->b_size,
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};
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struct block_device *bdev = bh->b_bdev;
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void *vto;
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if (dax_get_addr(bh, &vfrom, blkbits) < 0)
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return -EIO;
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if (dax_map_atomic(bdev, &dax) < 0)
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return PTR_ERR(dax.addr);
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vto = kmap_atomic(to);
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copy_user_page(vto, (void __force *)vfrom, vaddr, to);
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copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
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kunmap_atomic(vto);
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dax_unmap_atomic(bdev, &dax);
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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 __pmem *addr;
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unsigned long pfn;
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struct address_space *mapping = inode->i_mapping;
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struct block_device *bdev = bh->b_bdev;
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struct blk_dax_ctl dax = {
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.sector = to_sector(bh, inode),
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.size = bh->b_size,
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};
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pgoff_t size;
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int error;
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@ -308,20 +351,18 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
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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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if (dax_map_atomic(bdev, &dax) < 0) {
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error = PTR_ERR(dax.addr);
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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_pmem(addr, PAGE_SIZE);
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clear_pmem(dax.addr, PAGE_SIZE);
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wmb_pmem();
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}
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dax_unmap_atomic(bdev, &dax);
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error = vm_insert_mixed(vma, vaddr, pfn);
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error = vm_insert_mixed(vma, vaddr, dax.pfn);
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out:
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i_mmap_unlock_read(mapping);
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@ -415,7 +456,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
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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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error = copy_user_bh(new_page, inode, &bh, 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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@ -527,11 +568,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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unsigned blkbits = inode->i_blkbits;
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unsigned long pmd_addr = address & PMD_MASK;
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bool write = flags & FAULT_FLAG_WRITE;
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long length;
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void __pmem *kaddr;
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struct block_device *bdev;
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pgoff_t size, pgoff;
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sector_t block, sector;
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unsigned long pfn;
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sector_t block;
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int result = 0;
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/* dax pmd mappings are broken wrt gup and fork */
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@ -559,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
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bh.b_size = PMD_SIZE;
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length = get_block(inode, block, &bh, write);
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if (length)
|
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if (get_block(inode, block, &bh, write) != 0)
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return VM_FAULT_SIGBUS;
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bdev = bh.b_bdev;
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i_mmap_lock_read(mapping);
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|
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/*
|
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|
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@ -616,32 +655,40 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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result = VM_FAULT_NOPAGE;
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spin_unlock(ptl);
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} else {
|
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sector = bh.b_blocknr << (blkbits - 9);
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length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
|
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bh.b_size);
|
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struct blk_dax_ctl dax = {
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.sector = to_sector(&bh, inode),
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.size = PMD_SIZE,
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};
|
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long length = dax_map_atomic(bdev, &dax);
|
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|
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if (length < 0) {
|
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result = VM_FAULT_SIGBUS;
|
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goto out;
|
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}
|
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if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
|
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if ((length < PMD_SIZE) || (dax.pfn & PG_PMD_COLOUR)) {
|
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dax_unmap_atomic(bdev, &dax);
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goto fallback;
|
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}
|
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|
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/*
|
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* TODO: teach vmf_insert_pfn_pmd() to support
|
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* 'pte_special' for pmds
|
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*/
|
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if (pfn_valid(pfn))
|
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if (pfn_valid(dax.pfn)) {
|
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dax_unmap_atomic(bdev, &dax);
|
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goto fallback;
|
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}
|
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|
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if (buffer_unwritten(&bh) || buffer_new(&bh)) {
|
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clear_pmem(kaddr, PMD_SIZE);
|
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clear_pmem(dax.addr, PMD_SIZE);
|
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wmb_pmem();
|
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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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result |= VM_FAULT_MAJOR;
|
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}
|
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dax_unmap_atomic(bdev, &dax);
|
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|
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result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
|
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result |= vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
|
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}
|
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|
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out:
|
||||
|
|
@ -743,12 +790,17 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
|
|||
if (err < 0)
|
||||
return err;
|
||||
if (buffer_written(&bh)) {
|
||||
void __pmem *addr;
|
||||
err = dax_get_addr(&bh, &addr, inode->i_blkbits);
|
||||
if (err < 0)
|
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return err;
|
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clear_pmem(addr + offset, length);
|
||||
struct block_device *bdev = bh.b_bdev;
|
||||
struct blk_dax_ctl dax = {
|
||||
.sector = to_sector(&bh, inode),
|
||||
.size = PAGE_CACHE_SIZE,
|
||||
};
|
||||
|
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if (dax_map_atomic(bdev, &dax) < 0)
|
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return PTR_ERR(dax.addr);
|
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clear_pmem(dax.addr + offset, length);
|
||||
wmb_pmem();
|
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dax_unmap_atomic(bdev, &dax);
|
||||
}
|
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|
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return 0;
|
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|
|
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|||
|
|
@ -1617,6 +1617,20 @@ static inline bool integrity_req_gap_front_merge(struct request *req,
|
|||
|
||||
#endif /* CONFIG_BLK_DEV_INTEGRITY */
|
||||
|
||||
/**
|
||||
* struct blk_dax_ctl - control and output parameters for ->direct_access
|
||||
* @sector: (input) offset relative to a block_device
|
||||
* @addr: (output) kernel virtual address for @sector populated by driver
|
||||
* @pfn: (output) page frame number for @addr populated by driver
|
||||
* @size: (input) number of bytes requested
|
||||
*/
|
||||
struct blk_dax_ctl {
|
||||
sector_t sector;
|
||||
void __pmem *addr;
|
||||
long size;
|
||||
unsigned long pfn;
|
||||
};
|
||||
|
||||
struct block_device_operations {
|
||||
int (*open) (struct block_device *, fmode_t);
|
||||
void (*release) (struct gendisk *, fmode_t);
|
||||
|
|
@ -1643,8 +1657,7 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
|
|||
extern int bdev_read_page(struct block_device *, sector_t, struct page *);
|
||||
extern int bdev_write_page(struct block_device *, sector_t, struct page *,
|
||||
struct writeback_control *);
|
||||
extern long bdev_direct_access(struct block_device *, sector_t,
|
||||
void __pmem **addr, unsigned long *pfn, long size);
|
||||
extern long bdev_direct_access(struct block_device *, struct blk_dax_ctl *);
|
||||
#else /* CONFIG_BLOCK */
|
||||
|
||||
struct block_device;
|
||||
|
|
|
|||
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