From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> --- fs/dax.c | 98 +++++++++++++++++----------------------------------------------- 1 file changed, 26 insertions(+), 72 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 494e8fb7a98f..3eb0cf176d69 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -44,6 +44,7 @@ /* The 'colour' (ie low bits) within a PMD of a page offset. */ #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) +#define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT) static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; @@ -89,10 +90,10 @@ static void *dax_radix_locked_entry(sector_t sector, unsigned long flags) DAX_ENTRY_LOCK); } -static unsigned int dax_radix_order(void *entry) +static unsigned int dax_entry_order(void *entry) { if (xa_to_value(entry) & DAX_PMD) - return PMD_SHIFT - PAGE_SHIFT; + return PMD_ORDER; return 0; } @@ -299,10 +300,11 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, { XA_STATE(xas, &mapping->pages, index); bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */ - void *entry, **slot; + void *entry; + xas_set_order(&xas, index, size_flag ? PMD_ORDER : 0); restart: - xa_lock_irq(&mapping->pages); + xas_lock_irq(&xas); entry = get_unlocked_mapping_entry(&xas); if (WARN_ON_ONCE(entry && !xa_is_value(entry))) { @@ -326,84 +328,36 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, } } - /* No entry for given index? Make sure radix tree is big enough. */ - if (!entry || pmd_downgrade) { - int err; - - if (pmd_downgrade) { - /* - * Make sure 'entry' remains valid while we drop - * xa_lock. - */ - entry = lock_slot(&xas); - } - - xa_unlock_irq(&mapping->pages); + if (pmd_downgrade) { + entry = lock_slot(&xas); /* * Besides huge zero pages the only other thing that gets * downgraded are empty entries which don't need to be * unmapped. */ - if (pmd_downgrade && dax_is_zero_entry(entry)) + if (dax_is_zero_entry(entry)) { + xas_pause(&xas); + xas_unlock_irq(&xas); unmap_mapping_range(mapping, (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); - - err = radix_tree_preload( - mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); - if (err) { - if (pmd_downgrade) - put_locked_mapping_entry(mapping, index); - return ERR_PTR(err); + xas_lock_irq(&xas); } - xa_lock_irq(&mapping->pages); - - if (!entry) { - /* - * We needed to drop the pages lock while calling - * radix_tree_preload() and we didn't have an entry to - * lock. See if another thread inserted an entry at - * our index during this time. - */ - entry = __radix_tree_lookup(&mapping->pages, index, - NULL, &slot); - if (entry) { - radix_tree_preload_end(); - xa_unlock_irq(&mapping->pages); - goto restart; - } - } - - if (pmd_downgrade) { - radix_tree_delete(&mapping->pages, index); - mapping->nrexceptional--; - dax_wake_entry(&xas, entry, true); - } - + xas_store(&xas, NULL); + mapping->nrexceptional--; + dax_wake_entry(&xas, entry, true); + } + if (!entry || pmd_downgrade) { entry = dax_radix_locked_entry(0, size_flag | DAX_EMPTY); - - err = __radix_tree_insert(&mapping->pages, index, - dax_radix_order(entry), entry); - radix_tree_preload_end(); - if (err) { - xa_unlock_irq(&mapping->pages); - /* - * Our insertion of a DAX entry failed, most likely - * because we were inserting a PMD entry and it - * collided with a PTE sized entry at a different - * index in the PMD range. We haven't inserted - * anything into the radix tree and have no waiters to - * wake. - */ - return ERR_PTR(err); - } - /* Good, we have inserted empty locked entry into the tree. */ - mapping->nrexceptional++; - xa_unlock_irq(&mapping->pages); - return entry; + xas_store(&xas, entry); + if (!xas_error(&xas)) + mapping->nrexceptional++; + } else { + entry = lock_slot(&xas); } - entry = lock_slot(&xas); out_unlock: - xa_unlock_irq(&mapping->pages); + xas_unlock_irq(&xas); + if (xas_nomem(&xas, GFP_NOIO)) + goto restart; return entry; } @@ -682,7 +636,7 @@ static int dax_writeback_one(struct block_device *bdev, * worry about partial PMD writebacks. */ sector = dax_radix_sector(entry); - size = PAGE_SIZE << dax_radix_order(entry); + size = PAGE_SIZE << dax_entry_order(entry); id = dax_read_lock(); ret = bdev_dax_pgoff(bdev, sector, size, &pgoff); -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html