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Message-ID: <20160201134410.GD2948@linux.intel.com>
Date: Mon, 1 Feb 2016 08:44:10 -0500
From: Matthew Wilcox <willy@...ux.intel.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: linux-nvdimm <linux-nvdimm@...1.01.org>,
Dave Chinner <david@...morbit.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Christoph Hellwig <hch@...radead.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
Jan Kara <jack@...e.com>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/2] dax: fix bdev NULL pointer dereferences
On Sun, Jan 31, 2016 at 01:32:47PM +1100, Matthew Wilcox wrote:
> On Fri, Jan 29, 2016 at 10:01:13PM -0800, Dan Williams wrote:
> > On Fri, Jan 29, 2016 at 9:28 PM, Matthew Wilcox <willy@...ux.intel.com> wrote:
> > > If we store the PFN of the underlying page instead, we don't have this
> > > problem. Instead, we have a different problem; of the device going
> > > away under us. I'm trying to find the code which tears down PTEs when
> > > the device goes away, and I'm not seeing it. What do we do about user
> > > mappings of the device?
> >
> > I deferred the dax tear down code until next cycle as Al rightly
> > pointed out some needed re-works:
> >
> > https://lists.01.org/pipermail/linux-nvdimm/2016-January/003995.html
>
> Thanks; I eventually found it in my email somewhere over the Pacific.
>
> I did probably 70% of the work needed to switch the radix tree over to
> storing PFNs instead of sectors. It seems viable, though it's a big
> change from where we are today:
70%?! Hah. I'd done maybe 50%. This isn't everything needed; I still
need to write radix_tree_replace(). But it's enough to get a flavour for
where this line of thinking takes us. I think it ends up being cleaner
code, and possibly better performing. I also think it points us back
in the direction of wanting an address_space operation to return a PFN
for the radix tree instead of handling buffer_heads directly in dax.c.
Ah well. Time to sleep ...
>From 0321c30eeb189ad2da8dcc25623419e2ba9c6cee Mon Sep 17 00:00:00 2001
From: Matthew Wilcox <matthew.r.wilcox@...el.com>
Date: Sun, 31 Jan 2016 13:38:21 +1100
Subject: [PATCH] Giant non-compiling mess
Note that clear_pmem needs to be updated to set the needs_wmb() flag.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
---
fs/dax.c | 1127 +++++++++++++++++++++-----------------------
include/linux/dax.h | 3 +-
include/linux/pfn_t.h | 41 +-
include/linux/radix-tree.h | 9 -
include/linux/sched.h | 1 +
5 files changed, 565 insertions(+), 616 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index e9701d6..38b92b5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -25,12 +25,132 @@
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/pagevec.h>
+#include <linux/pfn_t.h>
#include <linux/pmem.h>
+#include <linux/preempt.h>
#include <linux/sched.h>
+#include <linux/sizes.h>
#include <linux/uio.h>
#include <linux/vmstat.h>
-#include <linux/pfn_t.h>
-#include <linux/sizes.h>
+
+/*
+ * 32-bit architectures want to override this to actually map/unmap
+ * their persistent memory. ARM, SPARC & MIPS also want to override it
+ * to map the PFN at an address that uses the same cachelines as the
+ * userspace mapping (that's what 'index' is for)
+ */
+static void *dax_map_pfn(pfn_t pfn, unsigned long index)
+{
+ if (is_bad_pfn_t(pfn))
+ return NULL;
+ preempt_disable();
+ pagefault_disable();
+ return pfn_to_kaddr(pfn_t_to_pfn(pfn));
+}
+
+static void dax_unmap_pfn(void *addr)
+{
+ pagefault_enable();
+ preempt_enable();
+}
+
+/*
+ * DAX uses the 'exceptional' entries to store PFNs in the radix tree.
+ * Bit 0 is clear (the radix tree uses this for its own purposes). Bit
+ * 1 is set (to indicate an exceptional entry). Bits 2 & 3 are PFN_DEV
+ * and PFN_MAP. The top two bits denote the size of the entry (PTE, PMD,
+ * PUD, one reserved). That leaves us 26 bits on 32-bit systems and 58
+ * bits on 64-bit systems, able to address 256GB and 1024EB respectively.
+ */
+#define RADIX_DAX_SIZE_MASK (0x3UL << (BITS_PER_LONG - 2))
+#define RADIX_TREE_MASK (RADIX_TREE_INDIRECT_PTR | \
+ RADIX_TREE_EXCEPTIONAL_ENTRY)
+#define RADIX_DAX_PFN_MASK (~(RADIX_DAX_SIZE_MASK | RADIX_TREE_MASK))
+#define RADIX_DAX_SHIFT 4
+#define RADIX_DAX_PTE (0x0UL << (BITS_PER_LONG - 2))
+#define RADIX_DAX_PMD (0x1UL << (BITS_PER_LONG - 2))
+#define RADIX_DAX_PUD (0x2UL << (BITS_PER_LONG - 2))
+#define RADIX_DAX_SIZE(entry) ((unsigned long)entry & RADIX_DAX_SIZE_MASK)
+#define RADIX_DAX_ENTRY(pfn, size) \
+ ((void *)((pfn_t_to_pfn(pfn) << RADIX_DAX_SHIFT) | size))
+
+/* The 'colour' (ie low bits) within a PMD/PUD of a page offset. */
+#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_CACHE_SHIFT) - 1)
+#define PG_PUD_COLOUR ((PUD_SIZE >> PAGE_CACHE_SHIFT) - 1)
+
+static pfn_t radix_to_pfn_t(void *entry, pgoff_t index)
+{
+ pfn_t pfn = { .val = (unsigned long)entry & RADIX_DAX_PFN_MASK };
+ unsigned offset = 0;
+
+ if (RADIX_DAX_SIZE(entry) == RADIX_DAX_PMD)
+ offset = index & PG_PMD_COLOUR;
+ else if (RADIX_DAX_SIZE(entry) == RADIX_DAX_PUD)
+ offset = index & PG_PUD_COLOUR;
+
+ return pfn_t_add(pfn, offset);
+}
+
+static void *pfn_to_radix(pfn_t pfn, unsigned long size)
+{
+ unsigned long value = pfn.val;
+ BUG_ON(value & RADIX_DAX_PFN_MASK);
+ return (void *)(value | size);
+}
+
+static unsigned size_to_order(unsigned long size)
+{
+ switch (size) {
+ case RADIX_DAX_PTE: return 0;
+ case RADIX_DAX_PMD: return PMD_SHIFT - PAGE_SHIFT;
+ case RADIX_DAX_PUD: return PUD_SHIFT - PAGE_SHIFT;
+ }
+ BUG();
+}
+
+static unsigned size_to_bytes(unsigned long size)
+{
+ switch (size) {
+ case RADIX_DAX_PTE: return PAGE_CACHE_SIZE;
+ case RADIX_DAX_PMD: return PMD_SIZE;
+ case RADIX_DAX_PUD: return PUD_SIZE;
+ }
+ BUG();
+}
+
+static int dax_add_radix_entry(struct address_space *mapping, pgoff_t index,
+ pfn_t pfn, unsigned long size, bool dirty)
+{
+ struct radix_tree_root *page_tree = &mapping->page_tree;
+ int count = 0;
+ void *entry;
+ unsigned order = size_to_order(size);
+
+ if (dirty)
+ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+
+ spin_lock_irq(&mapping->tree_lock);
+ entry = radix_tree_lookup(page_tree, index);
+ if (!radix_tree_exceptional_entry(entry)) {
+ count = -EEXIST;
+ goto unlock;
+ } else if (entry) {
+ if (size <= RADIX_DAX_SIZE(entry))
+ goto dirty;
+ }
+ count = radix_tree_replace(page_tree, index, order,
+ pfn_to_radix(pfn, size));
+ if (count < 0)
+ goto unlock;
+
+ mapping->nrexceptional -= (count - 1);
+ dirty:
+ if (dirty)
+ radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
+ unlock:
+ spin_unlock_irq(&mapping->tree_lock);
+ return count;
+}
static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
{
@@ -58,17 +178,235 @@ static void dax_unmap_atomic(struct block_device *bdev,
blk_queue_exit(bdev->bd_queue);
}
+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 bool buffer_written(struct buffer_head *bh)
+{
+ return buffer_mapped(bh) && !buffer_unwritten(bh);
+}
+
+static int dax_replace_hole(struct address_space *mapping, pgoff_t index,
+ unsigned long size, pfn_t pfn)
+{
+ unsigned order = size_to_order(size);
+ int i, error;
+
+ for (i = 0; i < (1 << order); i++) {
+ struct page *page;
+ repeat:
+ page = find_get_entry(mapping, index + i);
+ if (!page || radix_tree_exceptional_entry(page))
+ continue;
+
+ lock_page(page);
+ if (unlikely(page->mapping != mapping)) {
+ unlock_page(page);
+ page_cache_release(page);
+ goto repeat;
+ }
+
+ delete_from_page_cache(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+
+ /*
+ * Somebody else could look in the radix tree and find nothing.
+ * It's harmless though; they'll find the correct pfn by calling
+ * the filesystem.
+ */
+ error = dax_add_radix_entry(mapping, index, pfn, size, true);
+
+ unmap_mapping_range(mapping, index << PAGE_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
+
+ return error;
+}
+
+static int dax_add_pfn_sized(struct address_space *mapping, pgoff_t index,
+ size_t size, bool write, pfn_t pfn,
+ unsigned long radix_size, unsigned entry_size)
+{
+ int error;
+ bool report = true;
+
+ while (size >= entry_size) {
+ error = dax_add_radix_entry(mapping, index, pfn,
+ radix_size, write);
+ if (error == -EEXIST)
+ error = dax_replace_hole(mapping, index, radix_size,
+ pfn);
+ if (error)
+ break;
+ report = false;
+
+ size -= entry_size;
+ pfn = pfn_t_add(pfn, entry_size / PAGE_CACHE_SIZE);
+ index += entry_size / PAGE_CACHE_SIZE;
+ }
+
+ return report ? error : 0;
+}
+
+static int dax_add_pfn_entries(struct address_space *mapping, pgoff_t index,
+ size_t size, bool write, pfn_t pfn)
+{
+ int error = 0;
+ int called = 0;
+ size_t max;
+
+ max = (PG_PMD_COLOUR + 1 - index) << PAGE_CACHE_SHIFT;
+ if (index & PG_PMD_COLOUR) {
+ error = dax_add_pfn_sized(mapping, index, min(size, max),
+ write, pfn, RADIX_DAX_PTE, PAGE_CACHE_SIZE);
+ called++;
+ }
+ size -= min(size, max);
+ if (error || !size)
+ goto out;
+ index += max >> PAGE_CACHE_SHIFT;
+
+ max = (PG_PUD_COLOUR + 1 - index) << PAGE_CACHE_SHIFT;
+ if (index & PG_PUD_COLOUR) {
+ error = dax_add_pfn_sized(mapping, index, min(size, max),
+ write, pfn, RADIX_DAX_PMD, PMD_SIZE);
+ called++;
+ }
+ size -= min(size, max);
+ if (error || !size)
+ goto out;
+ index += max >> PMD_SHIFT;
+
+ error = dax_add_pfn_sized(mapping, index, size,
+ write, pfn, RADIX_DAX_PUD, PUD_SIZE);
+ called++;
+ index += size >> PUD_SHIFT;
+ size = size & ~PMD_MASK;
+ if (error || !size)
+ goto out;
+
+ error = dax_add_pfn_sized(mapping, index, size,
+ write, pfn, RADIX_DAX_PMD, PMD_SIZE);
+ index += size >> PMD_SHIFT;
+ size = size & ~PAGE_CACHE_MASK;
+ if (error || !size)
+ return 0;
+
+ error = dax_add_pfn_sized(mapping, index, size,
+ write, pfn, RADIX_DAX_PTE, PAGE_CACHE_SIZE);
+ out:
+ if (called > 1)
+ error = 0;
+ return error;
+}
+
+/*
+ * Populate the page cache with as many pfns as the filesystem is willing
+ * to tell us about from a single call to get_block, starting at @index and
+ * continuing up to @max bytes.
+ */
+static int dax_create_pfns(struct address_space *mapping, pgoff_t index,
+ unsigned max, bool write, pfn_t *pfn,
+ get_block_t get_block, struct buffer_head *bh)
+{
+ struct inode *inode = mapping->host;
+ unsigned blkbits = inode->i_blkbits;
+ sector_t block = index << (PAGE_CACHE_SHIFT - blkbits);
+ struct blk_dax_ctl dax;
+ int error, result = 0;
+
+ bh->b_size = max;
+ bh->b_state = 0;
+ error = get_block(inode, block, bh, write);
+ if (error)
+ goto error;
+
+ if (!buffer_written(bh))
+ goto hole;
+
+ dax.sector = to_sector(bh, inode);
+ dax.size = bh->b_size;
+ error = dax_map_atomic(bh->b_bdev, &dax);
+ if (error < 0)
+ goto error;
+
+ /*
+ * We may be about to write data to it, but now it's allocated,
+ * and another thread will be able to find it in the page cache,
+ * so we have to zero it otherwise there's a write vs fault race
+ * that could expose stale data to an application.
+ */
+ if (buffer_unwritten(bh) || buffer_new(bh)) {
+ clear_pmem(dax.addr, bh->b_size);
+ result = 1;
+ }
+
+ dax_unmap_atomic(bh->b_bdev, &dax);
+
+ error = dax_add_pfn_entries(mapping, index, bh->b_size,
+ write, dax.pfn);
+
+ /*
+ * Even if we had an error adding the PFN to the radix tree,
+ * the PFN is still good, so return it.
+ */
+ *pfn = dax.pfn;
+ return error ? error : result;
+
+ hole:
+ error:
+ *pfn = bad_pfn_t;
+ return error;
+}
+
+/*
+ * Returns either a negative errno, 0 if no allocation had to be performed,
+ * or 1 if the filesystem allocated a block.
+ */
+static int dax_get_pfn(struct address_space *mapping, pgoff_t index,
+ size_t len, bool write, pfn_t *pfn,
+ get_block_t get_block, struct buffer_head *bh)
+{
+ void *entry;
+
+ rcu_read_lock();
+ entry = radix_tree_lookup(&mapping->page_tree, index);
+ rcu_read_unlock();
+
+ if (radix_tree_exceptional_entry(entry)) {
+ *pfn = radix_to_pfn_t(entry, index);
+ return 0;
+ }
+
+ if (entry) {
+ if (write)
+ return dax_create_pfns(mapping, index, len, true, pfn,
+ get_block, bh);
+ } else {
+ return dax_create_pfns(mapping, index, len, write, pfn,
+ get_block, bh);
+ }
+
+ *pfn = bad_pfn_t;
+ return 0;
+}
+
/*
* 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 block_device *bdev, sector_t sector, long size)
{
- struct block_device *bdev = inode->i_sb->s_bdev;
struct blk_dax_ctl dax = {
- .sector = block << (inode->i_blkbits - 9),
- .size = _size,
+ .sector = sector,
+ .size = size,
};
might_sleep();
@@ -91,133 +429,52 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long _size)
}
EXPORT_SYMBOL_GPL(dax_clear_blocks);
-/* 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)
-{
- loff_t final = end - pos + first; /* The final byte of the buffer */
-
- if (first > 0)
- clear_pmem(addr, first);
- if (final < size)
- clear_pmem(addr + final, size - final);
-}
-
-static bool buffer_written(struct buffer_head *bh)
-{
- return buffer_mapped(bh) && !buffer_unwritten(bh);
-}
-
-/*
- * When ext4 encounters a hole, it returns without modifying the buffer_head
- * which means that we can't trust b_size. To cope with this, we set b_state
- * to 0 before calling get_block and, if any bit is set, we know we can trust
- * b_size. Unfortunate, really, since ext4 knows precisely how long a hole is
- * and would save us time calling get_block repeatedly.
- */
-static bool buffer_size_valid(struct buffer_head *bh)
-{
- return bh->b_state != 0;
-}
-
-
-static 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)
+ loff_t start, loff_t end,
+ get_block_t get_block, struct buffer_head *bh)
{
- 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),
- };
+ loff_t pos = start;
+ int error = 0;
+ const int rw = iov_iter_rw(iter);
if (rw == READ)
end = min(end, i_size_read(inode));
- while (pos < end) {
- size_t len;
- if (pos == max) {
- unsigned blkbits = inode->i_blkbits;
- long page = pos >> PAGE_SHIFT;
- sector_t block = page << (PAGE_SHIFT - blkbits);
- unsigned first = pos - (block << blkbits);
- long size;
-
- if (pos == bh_max) {
- bh->b_size = PAGE_ALIGN(end - pos);
- bh->b_state = 0;
- 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_blocknr += done >> blkbits;
- bh->b_size -= done;
- }
+ while (!error && pos < end) {
+ pgoff_t pgoff = pos >> PAGE_CACHE_SHIFT;
+ unsigned off = pos & ~PAGE_CACHE_MASK;
+ size_t len = end - pos;
+ pfn_t pfn;
+ void __pmem *addr;
- hole = rw == READ && !buffer_written(bh);
- if (hole) {
- size = bh->b_size - first;
- } else {
- 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(dax.addr, map_len, first,
- pos, end);
- need_wmb = true;
- }
- dax.addr += first;
- size = map_len - first;
- }
- max = min(pos + size, end);
- }
+ error = dax_get_pfn(inode->i_mapping, pgoff, len, rw == WRITE,
+ &pfn, get_block, bh);
+ if (error < 0)
+ break;
+ addr = dax_map_pfn(pfn, pgoff) + off;
- if (iov_iter_rw(iter) == WRITE) {
- len = copy_from_iter_pmem(dax.addr, max - pos, iter);
- need_wmb = true;
- } else if (!hole)
- len = copy_to_iter((void __force *) dax.addr, max - pos,
- iter);
+ if (len > PAGE_CACHE_SIZE)
+ len = PAGE_CACHE_SIZE;
+
+ if (rw == WRITE) {
+ len = copy_from_iter_pmem(addr, len, iter);
+ current->needs_wmb = true;
+ } else if (addr)
+ len = copy_to_iter((void __force *) addr, len, iter);
else
- len = iov_iter_zero(max - pos, iter);
+ len = iov_iter_zero(len, iter);
+ dax_unmap_pfn(addr - off);
- if (!len) {
- rc = -EFAULT;
- break;
- }
+ if (!len)
+ error = -EFAULT;
pos += len;
- if (!IS_ERR(dax.addr))
- dax.addr += len;
}
- if (need_wmb)
+ if (current->needs_wmb)
wmb_pmem();
- dax_unmap_atomic(bdev, &dax);
- return (pos == start) ? rc : pos - start;
+ return (pos == start) ? error : pos - start;
}
/**
@@ -238,15 +495,14 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
* is in progress.
*/
ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
- struct iov_iter *iter, loff_t pos, get_block_t get_block,
- dio_iodone_t end_io, int flags)
+ struct iov_iter *iter, loff_t pos,
+ get_block_t get_block, dio_iodone_t end_io, int flags)
{
struct buffer_head bh;
ssize_t retval = -EINVAL;
loff_t end = pos + iov_iter_count(iter);
memset(&bh, 0, sizeof(bh));
- bh.b_bdev = inode->i_sb->s_bdev;
if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) {
struct address_space *mapping = inode->i_mapping;
@@ -277,124 +533,26 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
}
EXPORT_SYMBOL_GPL(dax_do_io);
-/*
- * The user has performed a load from a hole in the file. Allocating
- * a new page in the file would cause excessive storage usage for
- * workloads with sparse files. We allocate a page cache page instead.
- * We'll kick it out of the page cache if it's ever written to,
- * otherwise it will simply fall out of the page cache under memory
- * pressure without ever having been dirtied.
- */
-static int dax_load_hole(struct address_space *mapping, struct page *page,
- struct vm_fault *vmf)
+static int copy_user_pfn(struct vm_fault *vmf, pfn_t pfn)
{
- if (!page)
- page = find_or_create_page(mapping, vmf->pgoff,
- vmf->gfp_mask | __GFP_ZERO);
- if (!page)
- return VM_FAULT_OOM;
- vmf->page = page;
- return VM_FAULT_LOCKED;
-}
+ void *vto, *vfrom;
-static int copy_user_bh(struct page *to, struct inode *inode,
- struct buffer_head *bh, unsigned long vaddr)
-{
- 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_map_atomic(bdev, &dax) < 0)
- return PTR_ERR(dax.addr);
- vto = kmap_atomic(to);
- copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
+ vfrom = dax_map_pfn(pfn, vmf->pgoff);
+ vto = kmap_atomic(vmf->cow_page);
+ copy_user_page(vto, vfrom, (unsigned long)vmf->virtual_address,
+ vmf->cow_page);
kunmap_atomic(vto);
- dax_unmap_atomic(bdev, &dax);
+ dax_unmap_pfn(vfrom);
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);
+ unsigned size = RADIX_DAX_SIZE(entry);
struct radix_tree_node *node;
- struct blk_dax_ctl dax;
+ void __pmem *addr;
void **slot;
int ret = 0;
@@ -412,38 +570,14 @@ static int dax_writeback_one(struct block_device *bdev,
/* 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);
+ addr = dax_map_pfn(radix_to_pfn_t(entry, index), index);
+ wb_cache_pmem(addr, size_to_bytes(size));
+ dax_unmap_pfn(addr);
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;
@@ -459,27 +593,17 @@ int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
{
struct inode *inode = mapping->host;
struct block_device *bdev = inode->i_sb->s_bdev;
- pgoff_t start_index, end_index, pmd_index;
+ pgoff_t start_index, end_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);
@@ -509,107 +633,80 @@ int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
}
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)
-{
- unsigned long vaddr = (unsigned long)vmf->virtual_address;
- 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,
- };
- int error;
-
- if (dax_map_atomic(bdev, &dax) < 0) {
- error = PTR_ERR(dax.addr);
- goto out;
- }
-
- if (buffer_unwritten(bh) || buffer_new(bh)) {
- 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, dax.pfn);
-
- out:
- return error;
-}
-
static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block, dax_iodone_t complete_unwritten)
{
- struct file *file = vma->vm_file;
- struct address_space *mapping = file->f_mapping;
+ struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
struct page *page;
+ pfn_t pfn;
struct buffer_head bh;
unsigned long vaddr = (unsigned long)vmf->virtual_address;
- unsigned blkbits = inode->i_blkbits;
- sector_t block;
pgoff_t size;
int error;
int major = 0;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (vmf->pgoff >= size)
return VM_FAULT_SIGBUS;
memset(&bh, 0, sizeof(bh));
- block = (sector_t)vmf->pgoff << (PAGE_CACHE_SHIFT - blkbits);
- bh.b_bdev = inode->i_sb->s_bdev;
- bh.b_size = PAGE_CACHE_SIZE;
repeat:
- page = find_get_page(mapping, vmf->pgoff);
- if (page) {
+ page = find_get_entry(mapping, vmf->pgoff);
+ if (radix_tree_exceptional_entry(page)) {
+ pfn = radix_to_pfn_t(page, vmf->pgoff);
+ page = NULL;
+ } else if (!page) {
+ error = dax_create_pfns(mapping, vmf->pgoff, PAGE_CACHE_SIZE,
+ write && !vmf->cow_page, &pfn, get_block, &bh);
+ if (error < 0)
+ goto out;
+
+ if (error) {
+ count_vm_event(PGMAJFAULT);
+ mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+ major = VM_FAULT_MAJOR;
+ error = 0;
+ }
+ } else {
if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
page_cache_release(page);
return VM_FAULT_RETRY;
- }
- if (unlikely(page->mapping != mapping)) {
+ } else if (unlikely(page->mapping != mapping)) {
unlock_page(page);
page_cache_release(page);
goto repeat;
}
}
- error = get_block(inode, block, &bh, 0);
- if (!error && (bh.b_size < PAGE_CACHE_SIZE))
- error = -EIO; /* fs corruption? */
- if (error)
- goto unlock_page;
+ if (is_bad_pfn_t(pfn) && !vmf->cow_page) {
+ /*
+ * Allocating a new page in the file would cause excessive
+ * storage usage for workloads with sparse files. We allocate
+ * a page cache page instead. We'll kick it out of the page
+ * cache if it's ever written to, otherwise it will simply
+ * fall out of the page cache under memory pressure without
+ * ever having been dirtied.
+ */
+ if (!page)
+ page = find_or_create_page(mapping, vmf->pgoff,
+ vmf->gfp_mask | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+ vmf->page = page;
+ return VM_FAULT_LOCKED;
+ }
- if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
- if (vmf->flags & FAULT_FLAG_WRITE) {
- error = get_block(inode, block, &bh, 1);
- count_vm_event(PGMAJFAULT);
- mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
- major = VM_FAULT_MAJOR;
- if (!error && (bh.b_size < PAGE_CACHE_SIZE))
- error = -EIO;
+ if (vmf->cow_page) {
+ if (is_bad_pfn_t(pfn)) {
+ clear_user_highpage(vmf->cow_page, vaddr);
+ } else {
+ error = copy_user_pfn(vmf, pfn);
if (error)
goto unlock_page;
- } else {
- return dax_load_hole(mapping, page, vmf);
}
- }
-
- if (vmf->cow_page) {
- struct page *new_page = vmf->cow_page;
- if (buffer_written(&bh))
- error = copy_user_bh(new_page, inode, &bh, vaddr);
- else
- clear_user_highpage(new_page, vaddr);
- if (error)
- goto unlock_page;
vmf->page = page;
/*
@@ -625,18 +722,10 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
return VM_FAULT_LOCKED;
}
- /* Check we didn't race with a read fault installing a new page */
- if (!page && major)
- page = find_lock_page(mapping, vmf->pgoff);
+ if (current->needs_wmb)
+ wmb_pmem();
- if (page) {
- unmap_mapping_range(mapping, vmf->pgoff << PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE, 0);
- delete_from_page_cache(page);
- unlock_page(page);
- page_cache_release(page);
- page = NULL;
- }
+ error = vm_insert_mixed(vma, vaddr, pfn);
/*
* If we successfully insert the new mapping over an unwritten extent,
@@ -648,12 +737,11 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
* indicate what the callback should do via the uptodate variable, same
* as for normal BH based IO completions.
*/
- error = dax_insert_mapping(inode, &bh, vma, vmf);
if (buffer_unwritten(&bh)) {
if (complete_unwritten)
complete_unwritten(&bh, !error);
else
- WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
+ WARN_ON_ONCE(!write);
}
out:
@@ -673,12 +761,6 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-/*
- * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
- * more often than one might expect in the below function.
- */
-#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_CACHE_SHIFT) - 1)
-
static void __dax_dbg(struct buffer_head *bh, unsigned long address,
const char *reason, const char *fn)
{
@@ -697,98 +779,19 @@ static void __dax_dbg(struct buffer_head *bh, unsigned long address,
#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd")
-static int dax_insert_pmd_mapping(struct inode *inode, struct buffer_head *bh,
- struct vm_area_struct *vma, struct vm_fault *vmf)
-{
- int major = 0;
- struct blk_dax_ctl dax = {
- .sector = to_sector(bh, inode),
- .size = PMD_SIZE,
- };
- struct block_device *bdev = bh->b_bdev;
- bool write = vmf->flags & FAULT_FLAG_WRITE;
- unsigned long address = (unsigned long)vmf->virtual_address;
- long length = dax_map_atomic(bdev, &dax);
-
- if (length < 0)
- return VM_FAULT_SIGBUS;
- if (length < PMD_SIZE) {
- dax_pmd_dbg(bh, address, "dax-length too small");
- goto unmap;
- }
-
- if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
- dax_pmd_dbg(bh, address, "pfn unaligned");
- goto unmap;
- }
-
- if (!pfn_t_devmap(dax.pfn)) {
- dax_pmd_dbg(bh, address, "pfn not in memmap");
- goto unmap;
- }
-
- if (buffer_unwritten(bh) || buffer_new(bh)) {
- clear_pmem(dax.addr, PMD_SIZE);
- wmb_pmem();
- count_vm_event(PGMAJFAULT);
- mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
- major = 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) {
- int error = dax_radix_entry(vma->vm_file->f_mapping, vmf->pgoff,
- dax.sector, true, true);
- if (error) {
- dax_pmd_dbg(bh, address,
- "PMD radix insertion failed");
- goto fallback;
- }
- }
-
- 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);
- return major | vmf_insert_pfn_pmd(vma, address, vmf->pmd,
- dax.pfn, write);
- unmap:
- dax_unmap_atomic(bdev, &dax);
- fallback:
- count_vm_event(THP_FAULT_FALLBACK);
- return VM_FAULT_FALLBACK;
-}
-
static int dax_pmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block, dax_iodone_t complete_unwritten)
{
- struct file *file = vma->vm_file;
- struct address_space *mapping = file->f_mapping;
+ struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
+ void *entry;
+ pfn_t pfn;
struct buffer_head bh;
- unsigned blkbits = inode->i_blkbits;
- unsigned long address = (unsigned long)vmf->virtual_address;
- unsigned long pmd_addr = address & PMD_MASK;
- bool write = vmf->flags & FAULT_FLAG_WRITE;
+ unsigned long vaddr = (unsigned long)vmf->virtual_address;
+ unsigned long pmd_addr = vaddr & PMD_MASK;
pgoff_t size;
- sector_t block;
- int result;
- bool alloc = false;
+ int result = 0;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
/* dax pmd mappings require pfn_t_devmap() */
if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
@@ -796,17 +799,17 @@ static int dax_pmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
/* Fall back to PTEs if we're going to COW */
if (write && !(vma->vm_flags & VM_SHARED)) {
- split_huge_pmd(vma, vmf->pmd, address);
- dax_pmd_dbg(NULL, address, "cow write");
+ split_huge_pmd(vma, vmf->pmd, vaddr);
+ dax_pmd_dbg(NULL, vaddr, "cow write");
return VM_FAULT_FALLBACK;
}
/* If the PMD would extend outside the VMA */
if (pmd_addr < vma->vm_start) {
- dax_pmd_dbg(NULL, address, "vma start unaligned");
+ dax_pmd_dbg(NULL, vaddr, "vma start unaligned");
return VM_FAULT_FALLBACK;
}
if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
- dax_pmd_dbg(NULL, address, "vma end unaligned");
+ dax_pmd_dbg(NULL, vaddr, "vma end unaligned");
return VM_FAULT_FALLBACK;
}
@@ -815,76 +818,69 @@ static int dax_pmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
return VM_FAULT_SIGBUS;
/* If the PMD would cover blocks out of the file */
if ((vmf->pgoff | PG_PMD_COLOUR) >= size) {
- dax_pmd_dbg(NULL, address,
+ dax_pmd_dbg(NULL, vaddr,
"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)vmf->pgoff << (PAGE_CACHE_SHIFT - blkbits);
-
- bh.b_size = PMD_SIZE;
-
- if (get_block(inode, block, &bh, 0) != 0)
- return VM_FAULT_SIGBUS;
-
- if (!buffer_mapped(&bh) && write) {
- if (get_block(inode, block, &bh, 1) != 0)
- return VM_FAULT_SIGBUS;
- alloc = true;
- }
- /*
- * 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) {
- dax_pmd_dbg(&bh, address, "allocated block too small");
- return VM_FAULT_FALLBACK;
- }
+ entry = find_get_entry(mapping, vmf->pgoff);
+ if (radix_tree_exceptional_entry(entry) &&
+ RADIX_DAX_SIZE(entry) >= RADIX_DAX_PMD) {
+ pfn = radix_to_pfn_t(entry, vmf->pgoff);
+ } else {
+ int error = dax_create_pfns(mapping, vmf->pgoff, PMD_SIZE,
+ write, &pfn, get_block, &bh);
+ if (error < 0)
+ goto fallback;
- /*
- * If we allocated new storage, make sure no process has any
- * zero pages covering this hole
- */
- if (alloc) {
- loff_t lstart = vmf->pgoff << PAGE_CACHE_SHIFT;
- loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */
+ if (error) {
+ count_vm_event(PGMAJFAULT);
+ mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+ result = VM_FAULT_MAJOR;
+ error = 0;
+ }
- truncate_pagecache_range(inode, lstart, lend);
+ /*
+ * We don't know if dax_create_pfns() was able to allocate
+ * a contiguous aligned chunk, or whether it was only able
+ * to do a partial allocation.
+ */
+ entry = find_get_entry(mapping, vmf->pgoff);
+ if (!radix_tree_exceptional_entry(entry) ||
+ RADIX_DAX_SIZE(entry) < RADIX_DAX_PMD)
+ goto fallback;
}
- if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
+ if (is_bad_pfn_t(pfn)) {
spinlock_t *ptl;
pmd_t entry, *pmd = vmf->pmd;
struct page *zero_page = get_huge_zero_page();
if (unlikely(!zero_page)) {
- dax_pmd_dbg(&bh, address, "no zero page");
+ dax_pmd_dbg(&bh, vaddr, "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");
+ dax_pmd_dbg(&bh, vaddr, "pmd already present");
goto fallback;
}
- dev_dbg(part_to_dev(bh.b_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 {
- result = dax_insert_pmd_mapping(inode, &bh, vma, vmf);
+ if (current->needs_wmb)
+ wmb_pmem();
+
+ result |= vmf_insert_pfn_pmd(vma, vaddr, vmf->pmd, pfn,
+ write);
}
out:
@@ -907,80 +903,21 @@ static int dax_pmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
#endif /* !CONFIG_TRANSPARENT_HUGEPAGE */
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-/*
- * The 'colour' (ie low bits) within a PUD of a page offset. This comes up
- * more often than one might expect in the below function.
- */
-#define PG_PUD_COLOUR ((PUD_SIZE >> PAGE_CACHE_SHIFT) - 1)
-
#define dax_pud_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pud")
-static int dax_insert_pud_mapping(struct inode *inode, struct buffer_head *bh,
- struct vm_area_struct *vma, struct vm_fault *vmf)
-{
- int major = 0;
- struct blk_dax_ctl dax = {
- .sector = to_sector(bh, inode),
- .size = PUD_SIZE,
- };
- struct block_device *bdev = bh->b_bdev;
- bool write = vmf->flags & FAULT_FLAG_WRITE;
- unsigned long address = (unsigned long)vmf->virtual_address;
- long length = dax_map_atomic(bdev, &dax);
-
- if (length < 0)
- return VM_FAULT_SIGBUS;
- if (length < PUD_SIZE) {
- dax_pud_dbg(bh, address, "dax-length too small");
- goto unmap;
- }
- if (pfn_t_to_pfn(dax.pfn) & PG_PUD_COLOUR) {
- dax_pud_dbg(bh, address, "pfn unaligned");
- goto unmap;
- }
-
- if (!pfn_t_devmap(dax.pfn)) {
- dax_pud_dbg(bh, address, "pfn not in memmap");
- goto unmap;
- }
-
- if (buffer_unwritten(bh) || buffer_new(bh)) {
- clear_pmem(dax.addr, PUD_SIZE);
- wmb_pmem();
- count_vm_event(PGMAJFAULT);
- mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
- major = VM_FAULT_MAJOR;
- }
- dax_unmap_atomic(bdev, &dax);
-
- 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);
- return major | vmf_insert_pfn_pud(vma, address, vmf->pud,
- dax.pfn, write);
- unmap:
- dax_unmap_atomic(bdev, &dax);
- count_vm_event(THP_FAULT_FALLBACK);
- return VM_FAULT_FALLBACK;
-}
-
static int dax_pud_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block, dax_iodone_t complete_unwritten)
{
- struct file *file = vma->vm_file;
- struct address_space *mapping = file->f_mapping;
+ struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
+ void *entry;
+ pfn_t pfn;
struct buffer_head bh;
- unsigned blkbits = inode->i_blkbits;
- unsigned long address = (unsigned long)vmf->virtual_address;
- unsigned long pud_addr = address & PUD_MASK;
- bool write = vmf->flags & FAULT_FLAG_WRITE;
+ unsigned long vaddr = (unsigned long)vmf->virtual_address;
+ unsigned long pud_addr = vaddr & PUD_MASK;
pgoff_t size;
- sector_t block;
- int result;
- bool alloc = false;
+ int result = 0;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
/* dax pud mappings require pfn_t_devmap() */
if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
@@ -988,17 +925,17 @@ static int dax_pud_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
/* Fall back to PTEs if we're going to COW */
if (write && !(vma->vm_flags & VM_SHARED)) {
- split_huge_pud(vma, vmf->pud, address);
- dax_pud_dbg(NULL, address, "cow write");
+ split_huge_pud(vma, vmf->pud, vaddr);
+ dax_pud_dbg(NULL, vaddr, "cow write");
return VM_FAULT_FALLBACK;
}
/* If the PUD would extend outside the VMA */
if (pud_addr < vma->vm_start) {
- dax_pud_dbg(NULL, address, "vma start unaligned");
+ dax_pud_dbg(NULL, vaddr, "vma start unaligned");
return VM_FAULT_FALLBACK;
}
if ((pud_addr + PUD_SIZE) > vma->vm_end) {
- dax_pud_dbg(NULL, address, "vma end unaligned");
+ dax_pud_dbg(NULL, vaddr, "vma end unaligned");
return VM_FAULT_FALLBACK;
}
@@ -1007,52 +944,50 @@ static int dax_pud_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
return VM_FAULT_SIGBUS;
/* If the PUD would cover blocks out of the file */
if ((vmf->pgoff | PG_PUD_COLOUR) >= size) {
- dax_pud_dbg(NULL, address,
+ dax_pud_dbg(NULL, vaddr,
"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)vmf->pgoff << (PAGE_CACHE_SHIFT - blkbits);
- bh.b_size = PUD_SIZE;
-
- if (get_block(inode, block, &bh, 0) != 0)
- return VM_FAULT_SIGBUS;
-
- if (!buffer_mapped(&bh) && write) {
- if (get_block(inode, block, &bh, 1) != 0)
- return VM_FAULT_SIGBUS;
- alloc = true;
- }
-
- /*
- * If the filesystem isn't willing to tell us the length of a hole,
- * just fall back to PMDs. Calling get_block 512 times in a loop
- * would be silly.
- */
- if (!buffer_size_valid(&bh) || bh.b_size < PUD_SIZE) {
- dax_pud_dbg(&bh, address, "allocated block too small");
- return VM_FAULT_FALLBACK;
- }
+ entry = find_get_entry(mapping, vmf->pgoff);
+ if (radix_tree_exceptional_entry(entry) &&
+ RADIX_DAX_SIZE(entry) >= RADIX_DAX_PUD) {
+ pfn = radix_to_pfn_t(entry, vmf->pgoff);
+ } else {
+ int error = dax_create_pfns(mapping, vmf->pgoff, PUD_SIZE,
+ write, &pfn, get_block, &bh);
+ if (error < 0)
+ goto fallback;
- /*
- * If we allocated new storage, make sure no process has any
- * zero pages covering this hole
- */
- if (alloc) {
- loff_t lstart = vmf->pgoff << PAGE_CACHE_SHIFT;
- loff_t lend = lstart + PUD_SIZE - 1; /* inclusive */
+ if (error) {
+ count_vm_event(PGMAJFAULT);
+ mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+ result = VM_FAULT_MAJOR;
+ error = 0;
+ }
- truncate_pagecache_range(inode, lstart, lend);
+ /*
+ * We don't know if dax_create_pfns() was able to allocate
+ * a contiguous aligned chunk, or whether it was only able
+ * to do a partial allocation.
+ */
+ entry = find_get_entry(mapping, vmf->pgoff);
+ if (!radix_tree_exceptional_entry(entry) ||
+ RADIX_DAX_SIZE(entry) < RADIX_DAX_PUD)
+ goto fallback;
}
- if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
- dax_pud_dbg(&bh, address, "no zero page");
+ if (is_bad_pfn_t(pfn)) {
+ dax_pud_dbg(&bh, vaddr, "no zero page");
goto fallback;
} else {
- result = dax_insert_pud_mapping(inode, &bh, vma, vmf);
+ if (current->needs_wmb)
+ wmb_pmem();
+
+ result |= vmf_insert_pfn_pud(vma, vaddr, vmf->pud, pfn,
+ write);
}
out:
@@ -1113,17 +1048,13 @@ EXPORT_SYMBOL_GPL(dax_fault);
*/
int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct file *file = vma->vm_file;
+ struct address_space *mapping = vma->vm_file->f_mapping;
+
+ spin_lock_irq(&mapping->tree_lock);
+ radix_tree_tag_set(&mapping->page_tree, vmf->pgoff,
+ PAGECACHE_TAG_DIRTY);
+ spin_unlock_irq(&mapping->tree_lock);
- /*
- * 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);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 8e58c36..0a6505d 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -5,9 +5,10 @@
#include <linux/mm.h>
#include <asm/pgtable.h>
+int dax_clear_blocks(struct block_device *, sector_t sector, long size);
+
ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *, loff_t,
get_block_t, dio_iodone_t, int flags);
-int dax_clear_blocks(struct inode *, sector_t block, long size);
int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
int dax_truncate_page(struct inode *, loff_t from, get_block_t);
int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t,
diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
index 07d18a8..95a7b50 100644
--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -8,21 +8,46 @@
* PFN_SG_LAST - pfn references a page and is the last scatterlist entry
* PFN_DEV - pfn is not covered by system memmap by default
* PFN_MAP - pfn has a dynamic page mapping established by a device driver
+ *
+ * Note that DAX uses the same format for its radix tree entries. The
+ * bottom two bits are used by the radix tree.
*/
-#define PFN_FLAGS_MASK (((unsigned long) ~PAGE_MASK) \
- << (BITS_PER_LONG - PAGE_SHIFT))
-#define PFN_SG_CHAIN (1UL << (BITS_PER_LONG - 1))
-#define PFN_SG_LAST (1UL << (BITS_PER_LONG - 2))
-#define PFN_DEV (1UL << (BITS_PER_LONG - 3))
-#define PFN_MAP (1UL << (BITS_PER_LONG - 4))
+#define PFN_FLAG_BITS 4
+#define PFN_FLAGS_MASK ((1 << PFN_FLAG_BITS) - 1)
+#define PFN_SG_CHAIN 0x1UL
+#define PFN_SG_LAST 0x2UL
+#define PFN_DEV 0x4UL
+#define PFN_MAP 0x8UL
static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, unsigned long flags)
{
- pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };
+ pfn_t pfn_t = { .val = (pfn << PFN_FLAG_BITS) |
+ (flags & PFN_FLAGS_MASK), };
return pfn_t;
}
+static inline __must_check pfn_t pfn_t_add(const pfn_t pfn, int val)
+{
+ pfn_t tmp = pfn;
+ tmp.val += val << PFN_FLAG_BITS;
+ return tmp;
+}
+
+/*
+ * It makes no sense to have both SG_CHAIN and SG_LAST set, so we could
+ * encode an errno in here if we need to. Note that you can't put a
+ * bad_pfn_t in the radix tree because the radix tree uses the bottom bit
+ * for its own purposes.
+ */
+#define bad_pfn_t ((pfn_t) { .val = -1 })
+
+static inline bool is_bad_pfn_t(pfn_t pfn)
+{
+ return ((pfn.val & (PFN_SG_CHAIN | PFN_SG_LAST)) ==
+ (PFN_SG_CHAIN | PFN_SG_LAST));
+}
+
/* a default pfn to pfn_t conversion assumes that @pfn is pfn_valid() */
static inline pfn_t pfn_to_pfn_t(unsigned long pfn)
{
@@ -38,7 +63,7 @@ static inline bool pfn_t_has_page(pfn_t pfn)
static inline unsigned long pfn_t_to_pfn(pfn_t pfn)
{
- return pfn.val & ~PFN_FLAGS_MASK;
+ return pfn.val >> PFN_FLAG_BITS;
}
static inline struct page *pfn_t_to_page(pfn_t pfn)
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 7c88ad1..57e7d87 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -51,15 +51,6 @@
#define RADIX_TREE_EXCEPTIONAL_ENTRY 2
#define RADIX_TREE_EXCEPTIONAL_SHIFT 2
-#define RADIX_DAX_MASK 0xf
-#define RADIX_DAX_SHIFT 4
-#define RADIX_DAX_PTE (0x4 | RADIX_TREE_EXCEPTIONAL_ENTRY)
-#define RADIX_DAX_PMD (0x8 | RADIX_TREE_EXCEPTIONAL_ENTRY)
-#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_MASK)
-#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT))
-#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \
- RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE)))
-
static inline int radix_tree_is_indirect_ptr(void *ptr)
{
return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6e95d8a..2cdfe76 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1476,6 +1476,7 @@ struct task_struct {
/* unserialized, strictly 'current' */
unsigned in_execve:1; /* bit to tell LSMs we're in execve */
unsigned in_iowait:1;
+ unsigned needs_wmb:1;
#ifdef CONFIG_MEMCG
unsigned memcg_may_oom:1;
#ifndef CONFIG_SLOB
--
2.7.0.rc3
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