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@xxxxxxxxxxxxxxx> 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@xxxxxxxxx> 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@xxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
