On Sat 23-12-17 16:56:38, Dan Williams wrote:
> In preparation for examining the busy state of dax pages in the truncate
> path, switch from sectors to pfns in the radix.
>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Looks good to me after comments are fixed as Ross asked. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> drivers/dax/super.c | 15 ++++++++--
> fs/dax.c | 75 ++++++++++++++++++---------------------------------
> 2 files changed, 39 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 473af694ad1c..516124ae1ccf 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -124,10 +124,19 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
> return len < 0 ? len : -EIO;
> }
>
> - if ((IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn))
> - || pfn_t_devmap(pfn))
> + if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) {
> + /*
> + * An arch that has enabled the pmem api should also
> + * have its drivers support pfn_t_devmap()
> + *
> + * This is a developer warning and should not trigger in
> + * production. dax_flush() will crash since it depends
> + * on being able to do (page_address(pfn_to_page())).
> + */
> + WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
> + } else if (pfn_t_devmap(pfn)) {
> /* pass */;
> - else {
> + } else {
> pr_debug("VFS (%s): error: dax support not enabled\n",
> sb->s_id);
> return -EOPNOTSUPP;
> diff --git a/fs/dax.c b/fs/dax.c
> index 78b72c48374e..54071cd27e8c 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -72,16 +72,15 @@ fs_initcall(init_dax_wait_table);
> #define RADIX_DAX_ZERO_PAGE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
> #define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
>
> -static unsigned long dax_radix_sector(void *entry)
> +static unsigned long dax_radix_pfn(void *entry)
> {
> return (unsigned long)entry >> RADIX_DAX_SHIFT;
> }
>
> -static void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
> +static void *dax_radix_locked_entry(unsigned long pfn, unsigned long flags)
> {
> return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
> - ((unsigned long)sector << RADIX_DAX_SHIFT) |
> - RADIX_DAX_ENTRY_LOCK);
> + (pfn << RADIX_DAX_SHIFT) | RADIX_DAX_ENTRY_LOCK);
> }
>
> static unsigned int dax_radix_order(void *entry)
> @@ -525,12 +524,13 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
> */
> static void *dax_insert_mapping_entry(struct address_space *mapping,
> struct vm_fault *vmf,
> - void *entry, sector_t sector,
> + void *entry, pfn_t pfn_t,
> unsigned long flags, bool dirty)
> {
> struct radix_tree_root *page_tree = &mapping->page_tree;
> - void *new_entry;
> + unsigned long pfn = pfn_t_to_pfn(pfn_t);
> pgoff_t index = vmf->pgoff;
> + void *new_entry;
>
> if (dirty)
> __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
> @@ -547,7 +547,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
> }
>
> spin_lock_irq(&mapping->tree_lock);
> - new_entry = dax_radix_locked_entry(sector, flags);
> + new_entry = dax_radix_locked_entry(pfn, flags);
>
> if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
> /*
> @@ -659,17 +659,14 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
> i_mmap_unlock_read(mapping);
> }
>
> -static int dax_writeback_one(struct block_device *bdev,
> - struct dax_device *dax_dev, struct address_space *mapping,
> - pgoff_t index, void *entry)
> +static int dax_writeback_one(struct dax_device *dax_dev,
> + struct address_space *mapping, pgoff_t index, void *entry)
> {
> struct radix_tree_root *page_tree = &mapping->page_tree;
> - void *entry2, **slot, *kaddr;
> - long ret = 0, id;
> - sector_t sector;
> - pgoff_t pgoff;
> + void *entry2, **slot;
> + unsigned long pfn;
> + long ret = 0;
> size_t size;
> - pfn_t pfn;
>
> /*
> * A page got tagged dirty in DAX mapping? Something is seriously
> @@ -688,7 +685,7 @@ static int dax_writeback_one(struct block_device *bdev,
> * compare sectors as we must not bail out due to difference in lockbit
> * or entry type.
> */
> - if (dax_radix_sector(entry2) != dax_radix_sector(entry))
> + if (dax_radix_pfn(entry2) != dax_radix_pfn(entry))
> goto put_unlocked;
> if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
> dax_is_zero_entry(entry))) {
> @@ -718,29 +715,11 @@ static int dax_writeback_one(struct block_device *bdev,
> * 'entry'. This allows us to flush for PMD_SIZE and not have to
> * worry about partial PMD writebacks.
> */
> - sector = dax_radix_sector(entry);
> + pfn = dax_radix_pfn(entry);
> size = PAGE_SIZE << dax_radix_order(entry);
>
> - id = dax_read_lock();
> - ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
> - if (ret)
> - goto dax_unlock;
> -
> - /*
> - * dax_direct_access() may sleep, so cannot hold tree_lock over
> - * its invocation.
> - */
> - ret = dax_direct_access(dax_dev, pgoff, size / PAGE_SIZE, &kaddr, &pfn);
> - if (ret < 0)
> - goto dax_unlock;
> -
> - if (WARN_ON_ONCE(ret < size / PAGE_SIZE)) {
> - ret = -EIO;
> - goto dax_unlock;
> - }
> -
> - dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn));
> - dax_flush(dax_dev, kaddr, size);
> + dax_mapping_entry_mkclean(mapping, index, pfn);
> + dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size);
> /*
> * After we have flushed the cache, we can clear the dirty tag. There
> * cannot be new dirty data in the pfn after the flush has completed as
> @@ -751,8 +730,6 @@ static int dax_writeback_one(struct block_device *bdev,
> radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
> spin_unlock_irq(&mapping->tree_lock);
> trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT);
> - dax_unlock:
> - dax_read_unlock(id);
> put_locked_mapping_entry(mapping, index);
> return ret;
>
> @@ -810,8 +787,8 @@ int dax_writeback_mapping_range(struct address_space *mapping,
> break;
> }
>
> - ret = dax_writeback_one(bdev, dax_dev, mapping,
> - indices[i], pvec.pages[i]);
> + ret = dax_writeback_one(dax_dev, mapping, indices[i],
> + pvec.pages[i]);
> if (ret < 0) {
> mapping_set_error(mapping, ret);
> goto out;
> @@ -879,6 +856,7 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
> int ret = VM_FAULT_NOPAGE;
> struct page *zero_page;
> void *entry2;
> + pfn_t pfn;
>
> zero_page = ZERO_PAGE(0);
> if (unlikely(!zero_page)) {
> @@ -886,14 +864,15 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
> goto out;
> }
>
> - entry2 = dax_insert_mapping_entry(mapping, vmf, entry, 0,
> + pfn = page_to_pfn_t(zero_page);
> + entry2 = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
> RADIX_DAX_ZERO_PAGE, false);
> if (IS_ERR(entry2)) {
> ret = VM_FAULT_SIGBUS;
> goto out;
> }
>
> - vm_insert_mixed(vmf->vma, vaddr, page_to_pfn_t(zero_page));
> + vm_insert_mixed(vmf->vma, vaddr, pfn);
> out:
> trace_dax_load_hole(inode, vmf, ret);
> return ret;
> @@ -1200,8 +1179,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> if (error < 0)
> goto error_finish_iomap;
>
> - entry = dax_insert_mapping_entry(mapping, vmf, entry,
> - dax_iomap_sector(&iomap, pos),
> + entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
> 0, write && !sync);
> if (IS_ERR(entry)) {
> error = PTR_ERR(entry);
> @@ -1286,13 +1264,15 @@ static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
> void *ret = NULL;
> spinlock_t *ptl;
> pmd_t pmd_entry;
> + pfn_t pfn;
>
> zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm);
>
> if (unlikely(!zero_page))
> goto fallback;
>
> - ret = dax_insert_mapping_entry(mapping, vmf, entry, 0,
> + pfn = page_to_pfn_t(zero_page);
> + ret = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
> RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE, false);
> if (IS_ERR(ret))
> goto fallback;
> @@ -1415,8 +1395,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> if (error < 0)
> goto finish_iomap;
>
> - entry = dax_insert_mapping_entry(mapping, vmf, entry,
> - dax_iomap_sector(&iomap, pos),
> + entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
> RADIX_DAX_PMD, write && !sync);
> if (IS_ERR(entry))
> goto finish_iomap;
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
