#include <linux/memcontrol.h>
#include <linux/mm.h>
#include <linux/mutex.h>
+#include <linux/pagevec.h>
#include <linux/pmem.h>
#include <linux/sched.h>
#include <linux/uio.h>
#include <linux/vmstat.h>
+#include <linux/pfn_t.h>
+#include <linux/sizes.h>
+
+static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
+{
+ struct request_queue *q = bdev->bd_queue;
+ long rc = -EIO;
+
+ dax->addr = (void __pmem *) ERR_PTR(-EIO);
+ if (blk_queue_enter(q, true) != 0)
+ return rc;
+
+ rc = bdev_direct_access(bdev, dax);
+ if (rc < 0) {
+ dax->addr = (void __pmem *) ERR_PTR(rc);
+ blk_queue_exit(q);
+ return rc;
+ }
+ return rc;
+}
+
+static void dax_unmap_atomic(struct block_device *bdev,
+ const struct blk_dax_ctl *dax)
+{
+ if (IS_ERR(dax->addr))
+ return;
+ blk_queue_exit(bdev->bd_queue);
+}
/*
* dax_clear_blocks() is called from within transaction context from XFS,
* and hence this means the stack from this point must follow GFP_NOFS
* semantics for all operations.
*/
-int dax_clear_blocks(struct inode *inode, sector_t block, long size)
+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);
+ struct blk_dax_ctl dax = {
+ .sector = block << (inode->i_blkbits - 9),
+ .size = _size,
+ };
might_sleep();
do {
- void __pmem *addr;
- unsigned long pfn;
- long count;
+ long count, sz;
- count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
+ count = dax_map_atomic(bdev, &dax);
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;
- clear_pmem(addr, pgsz);
- addr += pgsz;
- size -= pgsz;
- count -= pgsz;
- BUG_ON(pgsz & 511);
- sector += pgsz / 512;
- cond_resched();
- }
- } while (size);
+ sz = min_t(long, count, SZ_128K);
+ clear_pmem(dax.addr, sz);
+ dax.size -= sz;
+ dax.sector += sz / 512;
+ dax_unmap_atomic(bdev, &dax);
+ cond_resched();
+ } while (dax.size);
wmb_pmem();
return 0;
}
EXPORT_SYMBOL_GPL(dax_clear_blocks);
-static long dax_get_addr(struct buffer_head *bh, void __pmem **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);
-}
-
/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
loff_t pos, loff_t end)
return bh->b_state != 0;
}
+
+static sector_t to_sector(const struct buffer_head *bh,
+ const struct inode *inode)
+{
+ sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
+
+ return sector;
+}
+
static ssize_t dax_io(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 __pmem *addr;
- bool hole = false;
- bool need_wmb = false;
-
- if (iov_iter_rw(iter) != WRITE)
+ loff_t pos = start, max = start, bh_max = start;
+ bool hole = false, need_wmb = false;
+ struct block_device *bdev = NULL;
+ int rw = iov_iter_rw(iter), rc;
+ long map_len = 0;
+ struct blk_dax_ctl dax = {
+ .addr = (void __pmem *) ERR_PTR(-EIO),
+ };
+
+ if (rw == READ)
end = min(end, i_size_read(inode));
while (pos < end) {
if (pos == bh_max) {
bh->b_size = PAGE_ALIGN(end - pos);
bh->b_state = 0;
- retval = get_block(inode, block, bh,
- iov_iter_rw(iter) == WRITE);
- if (retval)
+ rc = get_block(inode, block, bh, rw == WRITE);
+ if (rc)
break;
if (!buffer_size_valid(bh))
bh->b_size = 1 << blkbits;
bh_max = pos - first + bh->b_size;
+ bdev = bh->b_bdev;
} else {
unsigned done = bh->b_size -
(bh_max - (pos - first));
bh->b_size -= done;
}
- hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
+ hole = rw == READ && !buffer_written(bh);
if (hole) {
- addr = NULL;
size = bh->b_size - first;
} else {
- retval = dax_get_addr(bh, &addr, blkbits);
- if (retval < 0)
+ dax_unmap_atomic(bdev, &dax);
+ dax.sector = to_sector(bh, inode);
+ dax.size = bh->b_size;
+ map_len = dax_map_atomic(bdev, &dax);
+ if (map_len < 0) {
+ rc = map_len;
break;
+ }
if (buffer_unwritten(bh) || buffer_new(bh)) {
- dax_new_buf(addr, retval, first, pos,
- end);
+ dax_new_buf(dax.addr, map_len, first,
+ pos, end);
need_wmb = true;
}
- addr += first;
- size = retval - first;
+ dax.addr += first;
+ size = map_len - first;
}
max = min(pos + size, end);
}
if (iov_iter_rw(iter) == WRITE) {
- len = copy_from_iter_pmem(addr, max - pos, iter);
+ len = copy_from_iter_pmem(dax.addr, max - pos, iter);
need_wmb = true;
} else if (!hole)
- len = copy_to_iter((void __force *)addr, max - pos,
+ len = copy_to_iter((void __force *) dax.addr, max - pos,
iter);
else
len = iov_iter_zero(max - pos, iter);
if (!len) {
- retval = -EFAULT;
+ rc = -EFAULT;
break;
}
pos += len;
- addr += len;
+ if (!IS_ERR(dax.addr))
+ dax.addr += len;
}
if (need_wmb)
wmb_pmem();
+ dax_unmap_atomic(bdev, &dax);
- return (pos == start) ? retval : pos - start;
+ return (pos == start) ? rc : pos - start;
}
/**
return VM_FAULT_LOCKED;
}
-static int copy_user_bh(struct page *to, struct buffer_head *bh,
- unsigned blkbits, unsigned long vaddr)
+static int copy_user_bh(struct page *to, struct inode *inode,
+ struct buffer_head *bh, unsigned long vaddr)
{
- void __pmem *vfrom;
+ struct blk_dax_ctl dax = {
+ .sector = to_sector(bh, inode),
+ .size = bh->b_size,
+ };
+ struct block_device *bdev = bh->b_bdev;
void *vto;
- if (dax_get_addr(bh, &vfrom, blkbits) < 0)
- return -EIO;
+ if (dax_map_atomic(bdev, &dax) < 0)
+ return PTR_ERR(dax.addr);
vto = kmap_atomic(to);
- copy_user_page(vto, (void __force *)vfrom, vaddr, to);
+ copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
kunmap_atomic(vto);
+ dax_unmap_atomic(bdev, &dax);
return 0;
}
+#define NO_SECTOR -1
+#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_CACHE_SHIFT))
+
+static int dax_radix_entry(struct address_space *mapping, pgoff_t index,
+ sector_t sector, bool pmd_entry, bool dirty)
+{
+ struct radix_tree_root *page_tree = &mapping->page_tree;
+ pgoff_t pmd_index = DAX_PMD_INDEX(index);
+ int type, error = 0;
+ void *entry;
+
+ WARN_ON_ONCE(pmd_entry && !dirty);
+ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+
+ spin_lock_irq(&mapping->tree_lock);
+
+ entry = radix_tree_lookup(page_tree, pmd_index);
+ if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) {
+ index = pmd_index;
+ goto dirty;
+ }
+
+ entry = radix_tree_lookup(page_tree, index);
+ if (entry) {
+ type = RADIX_DAX_TYPE(entry);
+ if (WARN_ON_ONCE(type != RADIX_DAX_PTE &&
+ type != RADIX_DAX_PMD)) {
+ error = -EIO;
+ goto unlock;
+ }
+
+ if (!pmd_entry || type == RADIX_DAX_PMD)
+ goto dirty;
+
+ /*
+ * We only insert dirty PMD entries into the radix tree. This
+ * means we don't need to worry about removing a dirty PTE
+ * entry and inserting a clean PMD entry, thus reducing the
+ * range we would flush with a follow-up fsync/msync call.
+ */
+ radix_tree_delete(&mapping->page_tree, index);
+ mapping->nrexceptional--;
+ }
+
+ if (sector == NO_SECTOR) {
+ /*
+ * This can happen during correct operation if our pfn_mkwrite
+ * fault raced against a hole punch operation. If this
+ * happens the pte that was hole punched will have been
+ * unmapped and the radix tree entry will have been removed by
+ * the time we are called, but the call will still happen. We
+ * will return all the way up to wp_pfn_shared(), where the
+ * pte_same() check will fail, eventually causing page fault
+ * to be retried by the CPU.
+ */
+ goto unlock;
+ }
+
+ error = radix_tree_insert(page_tree, index,
+ RADIX_DAX_ENTRY(sector, pmd_entry));
+ if (error)
+ goto unlock;
+
+ mapping->nrexceptional++;
+ dirty:
+ if (dirty)
+ radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
+ unlock:
+ spin_unlock_irq(&mapping->tree_lock);
+ return error;
+}
+
+static int dax_writeback_one(struct block_device *bdev,
+ struct address_space *mapping, pgoff_t index, void *entry)
+{
+ struct radix_tree_root *page_tree = &mapping->page_tree;
+ int type = RADIX_DAX_TYPE(entry);
+ struct radix_tree_node *node;
+ struct blk_dax_ctl dax;
+ void **slot;
+ int ret = 0;
+
+ spin_lock_irq(&mapping->tree_lock);
+ /*
+ * Regular page slots are stabilized by the page lock even
+ * without the tree itself locked. These unlocked entries
+ * need verification under the tree lock.
+ */
+ if (!__radix_tree_lookup(page_tree, index, &node, &slot))
+ goto unlock;
+ if (*slot != entry)
+ goto unlock;
+
+ /* another fsync thread may have already written back this entry */
+ if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
+ goto unlock;
+
+ if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) {
+ ret = -EIO;
+ goto unlock;
+ }
+
+ dax.sector = RADIX_DAX_SECTOR(entry);
+ dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE);
+ spin_unlock_irq(&mapping->tree_lock);
+
+ /*
+ * We cannot hold tree_lock while calling dax_map_atomic() because it
+ * eventually calls cond_resched().
+ */
+ ret = dax_map_atomic(bdev, &dax);
+ if (ret < 0)
+ return ret;
+
+ if (WARN_ON_ONCE(ret < dax.size)) {
+ ret = -EIO;
+ goto unmap;
+ }
+
+ wb_cache_pmem(dax.addr, dax.size);
+
+ spin_lock_irq(&mapping->tree_lock);
+ radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
+ spin_unlock_irq(&mapping->tree_lock);
+ unmap:
+ dax_unmap_atomic(bdev, &dax);
+ return ret;
+
+ unlock:
+ spin_unlock_irq(&mapping->tree_lock);
+ return ret;
+}
+
+/*
+ * Flush the mapping to the persistent domain within the byte range of [start,
+ * end]. This is required by data integrity operations to ensure file data is
+ * on persistent storage prior to completion of the operation.
+ */
+int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
+ loff_t end)
+{
+ struct inode *inode = mapping->host;
+ struct block_device *bdev = inode->i_sb->s_bdev;
+ pgoff_t start_index, end_index, pmd_index;
+ pgoff_t indices[PAGEVEC_SIZE];
+ struct pagevec pvec;
+ bool done = false;
+ int i, ret = 0;
+ void *entry;
+
+ if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
+ return -EIO;
+
+ start_index = start >> PAGE_CACHE_SHIFT;
+ end_index = end >> PAGE_CACHE_SHIFT;
+ pmd_index = DAX_PMD_INDEX(start_index);
+
+ rcu_read_lock();
+ entry = radix_tree_lookup(&mapping->page_tree, pmd_index);
+ rcu_read_unlock();
+
+ /* see if the start of our range is covered by a PMD entry */
+ if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD)
+ start_index = pmd_index;
+
+ tag_pages_for_writeback(mapping, start_index, end_index);
+
+ pagevec_init(&pvec, 0);
+ while (!done) {
+ pvec.nr = find_get_entries_tag(mapping, start_index,
+ PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
+ pvec.pages, indices);
+
+ if (pvec.nr == 0)
+ break;
+
+ for (i = 0; i < pvec.nr; i++) {
+ if (indices[i] > end_index) {
+ done = true;
+ break;
+ }
+
+ ret = dax_writeback_one(bdev, mapping, indices[i],
+ pvec.pages[i]);
+ if (ret < 0)
+ return ret;
+ }
+ }
+ wmb_pmem();
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
+
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 __pmem *addr;
- unsigned long pfn;
+ struct address_space *mapping = inode->i_mapping;
+ struct block_device *bdev = bh->b_bdev;
+ struct blk_dax_ctl dax = {
+ .sector = to_sector(bh, inode),
+ .size = bh->b_size,
+ };
pgoff_t size;
int error;
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;
+ if (dax_map_atomic(bdev, &dax) < 0) {
+ error = PTR_ERR(dax.addr);
goto out;
}
if (buffer_unwritten(bh) || buffer_new(bh)) {
- clear_pmem(addr, PAGE_SIZE);
+ clear_pmem(dax.addr, PAGE_SIZE);
wmb_pmem();
}
+ dax_unmap_atomic(bdev, &dax);
+
+ error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false,
+ vmf->flags & FAULT_FLAG_WRITE);
+ if (error)
+ goto out;
- error = vm_insert_mixed(vma, vaddr, pfn);
+ error = vm_insert_mixed(vma, vaddr, dax.pfn);
out:
i_mmap_unlock_read(mapping);
if (vmf->cow_page) {
struct page *new_page = vmf->cow_page;
if (buffer_written(&bh))
- error = copy_user_bh(new_page, &bh, blkbits, vaddr);
+ error = copy_user_bh(new_page, inode, &bh, vaddr);
else
clear_user_highpage(new_page, vaddr);
if (error)
delete_from_page_cache(page);
unlock_page(page);
page_cache_release(page);
+ page = NULL;
}
/*
*/
#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
+static void __dax_dbg(struct buffer_head *bh, unsigned long address,
+ const char *reason, const char *fn)
+{
+ if (bh) {
+ char bname[BDEVNAME_SIZE];
+ bdevname(bh->b_bdev, bname);
+ pr_debug("%s: %s addr: %lx dev %s state %lx start %lld "
+ "length %zd fallback: %s\n", fn, current->comm,
+ address, bname, bh->b_state, (u64)bh->b_blocknr,
+ bh->b_size, reason);
+ } else {
+ pr_debug("%s: %s addr: %lx fallback: %s\n", fn,
+ current->comm, address, reason);
+ }
+}
+
+#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd")
+
int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmd, unsigned int flags, get_block_t get_block,
dax_iodone_t complete_unwritten)
unsigned blkbits = inode->i_blkbits;
unsigned long pmd_addr = address & PMD_MASK;
bool write = flags & FAULT_FLAG_WRITE;
- long length;
- void __pmem *kaddr;
+ struct block_device *bdev;
pgoff_t size, pgoff;
- sector_t block, sector;
- unsigned long pfn;
- int result = 0;
+ sector_t block;
+ int error, result = 0;
+ bool alloc = false;
- /* dax pmd mappings are broken wrt gup and fork */
+ /* dax pmd mappings require pfn_t_devmap() */
if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
return VM_FAULT_FALLBACK;
/* Fall back to PTEs if we're going to COW */
- if (write && !(vma->vm_flags & VM_SHARED))
+ if (write && !(vma->vm_flags & VM_SHARED)) {
+ split_huge_pmd(vma, pmd, address);
+ dax_pmd_dbg(NULL, address, "cow write");
return VM_FAULT_FALLBACK;
+ }
/* If the PMD would extend outside the VMA */
- if (pmd_addr < vma->vm_start)
+ if (pmd_addr < vma->vm_start) {
+ dax_pmd_dbg(NULL, address, "vma start unaligned");
return VM_FAULT_FALLBACK;
- if ((pmd_addr + PMD_SIZE) > vma->vm_end)
+ }
+ if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
+ dax_pmd_dbg(NULL, address, "vma end unaligned");
return VM_FAULT_FALLBACK;
+ }
pgoff = linear_page_index(vma, pmd_addr);
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (pgoff >= size)
return VM_FAULT_SIGBUS;
/* If the PMD would cover blocks out of the file */
- if ((pgoff | PG_PMD_COLOUR) >= size)
+ if ((pgoff | PG_PMD_COLOUR) >= size) {
+ dax_pmd_dbg(NULL, address,
+ "offset + huge page size > file size");
return VM_FAULT_FALLBACK;
+ }
memset(&bh, 0, sizeof(bh));
+ bh.b_bdev = inode->i_sb->s_bdev;
block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
bh.b_size = PMD_SIZE;
- length = get_block(inode, block, &bh, write);
- if (length)
+
+ if (get_block(inode, block, &bh, 0) != 0)
return VM_FAULT_SIGBUS;
- i_mmap_lock_read(mapping);
+
+ if (!buffer_mapped(&bh) && write) {
+ if (get_block(inode, block, &bh, 1) != 0)
+ return VM_FAULT_SIGBUS;
+ alloc = true;
+ }
+
+ bdev = bh.b_bdev;
/*
* If the filesystem isn't willing to tell us the length of a hole,
* just fall back to PTEs. Calling get_block 512 times in a loop
* would be silly.
*/
- if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
- goto fallback;
+ if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
+ dax_pmd_dbg(&bh, address, "allocated block too small");
+ return VM_FAULT_FALLBACK;
+ }
/*
* If we allocated new storage, make sure no process has any
* zero pages covering this hole
*/
- if (buffer_new(&bh)) {
- i_mmap_unlock_read(mapping);
- unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
- i_mmap_lock_read(mapping);
+ if (alloc) {
+ loff_t lstart = pgoff << PAGE_SHIFT;
+ loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */
+
+ truncate_pagecache_range(inode, lstart, lend);
}
+ i_mmap_lock_read(mapping);
+
/*
* If a truncate happened while we were allocating blocks, we may
* leave blocks allocated to the file that are beyond EOF. We can't
result = VM_FAULT_SIGBUS;
goto out;
}
- if ((pgoff | PG_PMD_COLOUR) >= size)
+ if ((pgoff | PG_PMD_COLOUR) >= size) {
+ dax_pmd_dbg(&bh, address,
+ "offset + huge page size > file size");
goto fallback;
+ }
if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
spinlock_t *ptl;
pmd_t entry;
struct page *zero_page = get_huge_zero_page();
- if (unlikely(!zero_page))
+ if (unlikely(!zero_page)) {
+ dax_pmd_dbg(&bh, address, "no zero page");
goto fallback;
+ }
ptl = pmd_lock(vma->vm_mm, pmd);
if (!pmd_none(*pmd)) {
spin_unlock(ptl);
+ dax_pmd_dbg(&bh, address, "pmd already present");
goto fallback;
}
+ dev_dbg(part_to_dev(bdev->bd_part),
+ "%s: %s addr: %lx pfn: <zero> sect: %llx\n",
+ __func__, current->comm, address,
+ (unsigned long long) to_sector(&bh, inode));
+
entry = mk_pmd(zero_page, vma->vm_page_prot);
entry = pmd_mkhuge(entry);
set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry);
result = VM_FAULT_NOPAGE;
spin_unlock(ptl);
} else {
- sector = bh.b_blocknr << (blkbits - 9);
- length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
- bh.b_size);
+ struct blk_dax_ctl dax = {
+ .sector = to_sector(&bh, inode),
+ .size = PMD_SIZE,
+ };
+ long length = dax_map_atomic(bdev, &dax);
+
if (length < 0) {
result = VM_FAULT_SIGBUS;
goto out;
}
- if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
+ if (length < PMD_SIZE) {
+ dax_pmd_dbg(&bh, address, "dax-length too small");
+ dax_unmap_atomic(bdev, &dax);
goto fallback;
+ }
+ if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
+ dax_pmd_dbg(&bh, address, "pfn unaligned");
+ dax_unmap_atomic(bdev, &dax);
+ goto fallback;
+ }
- /*
- * TODO: teach vmf_insert_pfn_pmd() to support
- * 'pte_special' for pmds
- */
- if (pfn_valid(pfn))
+ if (!pfn_t_devmap(dax.pfn)) {
+ dax_unmap_atomic(bdev, &dax);
+ dax_pmd_dbg(&bh, address, "pfn not in memmap");
goto fallback;
+ }
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
- int i;
- for (i = 0; i < PTRS_PER_PMD; i++)
- clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
+ clear_pmem(dax.addr, PMD_SIZE);
wmb_pmem();
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
result |= VM_FAULT_MAJOR;
}
+ dax_unmap_atomic(bdev, &dax);
+
+ /*
+ * For PTE faults we insert a radix tree entry for reads, and
+ * leave it clean. Then on the first write we dirty the radix
+ * tree entry via the dax_pfn_mkwrite() path. This sequence
+ * allows the dax_pfn_mkwrite() call to be simpler and avoid a
+ * call into get_block() to translate the pgoff to a sector in
+ * order to be able to create a new radix tree entry.
+ *
+ * The PMD path doesn't have an equivalent to
+ * dax_pfn_mkwrite(), though, so for a read followed by a
+ * write we traverse all the way through __dax_pmd_fault()
+ * twice. This means we can just skip inserting a radix tree
+ * entry completely on the initial read and just wait until
+ * the write to insert a dirty entry.
+ */
+ if (write) {
+ error = dax_radix_entry(mapping, pgoff, dax.sector,
+ true, true);
+ if (error) {
+ dax_pmd_dbg(&bh, address,
+ "PMD radix insertion failed");
+ goto fallback;
+ }
+ }
- result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
+ dev_dbg(part_to_dev(bdev->bd_part),
+ "%s: %s addr: %lx pfn: %lx sect: %llx\n",
+ __func__, current->comm, address,
+ pfn_t_to_pfn(dax.pfn),
+ (unsigned long long) dax.sector);
+ result |= vmf_insert_pfn_pmd(vma, address, pmd,
+ dax.pfn, write);
}
out:
* dax_pfn_mkwrite - handle first write to DAX page
* @vma: The virtual memory area where the fault occurred
* @vmf: The description of the fault
- *
*/
int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+ struct file *file = vma->vm_file;
- sb_start_pagefault(sb);
- file_update_time(vma->vm_file);
- sb_end_pagefault(sb);
+ /*
+ * We pass NO_SECTOR to dax_radix_entry() because we expect that a
+ * RADIX_DAX_PTE entry already exists in the radix tree from a
+ * previous call to __dax_fault(). We just want to look up that PTE
+ * entry using vmf->pgoff and make sure the dirty tag is set. This
+ * saves us from having to make a call to get_block() here to look
+ * up the sector.
+ */
+ dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, true);
return VM_FAULT_NOPAGE;
}
EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
if (err < 0)
return err;
if (buffer_written(&bh)) {
- void __pmem *addr;
- err = dax_get_addr(&bh, &addr, inode->i_blkbits);
- if (err < 0)
- return err;
- 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,
+ };
+
+ if (dax_map_atomic(bdev, &dax) < 0)
+ return PTR_ERR(dax.addr);
+ clear_pmem(dax.addr + offset, length);
wmb_pmem();
+ dax_unmap_atomic(bdev, &dax);
}
return 0;
projects / cascardo / linux.git / blobdiff