From b93b016313b3ba8003c3b8bb71f569af91f19fc7 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Tue, 10 Apr 2018 16:36:56 -0700 Subject: page cache: use xa_lock Remove the address_space ->tree_lock and use the xa_lock newly added to the radix_tree_root. Rename the address_space ->page_tree to ->i_pages, since we don't really care that it's a tree. [willy@infradead.org: fix nds32, fs/dax.c] Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org Signed-off-by: Matthew Wilcox Acked-by: Jeff Layton Cc: Darrick J. Wong Cc: Dave Chinner Cc: Ryusuke Konishi Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dax.c | 124 +++++++++++++++++++++++++++++++-------------------------------- 1 file changed, 60 insertions(+), 64 deletions(-) (limited to 'fs/dax.c') diff --git a/fs/dax.c b/fs/dax.c index a77394fe586e..aaec72ded1b6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -158,11 +158,9 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mo } /* - * We do not necessarily hold the mapping->tree_lock when we call this - * function so it is possible that 'entry' is no longer a valid item in the - * radix tree. This is okay because all we really need to do is to find the - * correct waitqueue where tasks might be waiting for that old 'entry' and - * wake them. + * @entry may no longer be the entry at the index in the mapping. + * The important information it's conveying is whether the entry at + * this index used to be a PMD entry. */ static void dax_wake_mapping_entry_waiter(struct address_space *mapping, pgoff_t index, void *entry, bool wake_all) @@ -174,7 +172,7 @@ static void dax_wake_mapping_entry_waiter(struct address_space *mapping, /* * Checking for locked entry and prepare_to_wait_exclusive() happens - * under mapping->tree_lock, ditto for entry handling in our callers. + * under the i_pages lock, ditto for entry handling in our callers. * So at this point all tasks that could have seen our entry locked * must be in the waitqueue and the following check will see them. */ @@ -183,41 +181,39 @@ static void dax_wake_mapping_entry_waiter(struct address_space *mapping, } /* - * Check whether the given slot is locked. The function must be called with - * mapping->tree_lock held + * Check whether the given slot is locked. Must be called with the i_pages + * lock held. */ static inline int slot_locked(struct address_space *mapping, void **slot) { unsigned long entry = (unsigned long) - radix_tree_deref_slot_protected(slot, &mapping->tree_lock); + radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); return entry & RADIX_DAX_ENTRY_LOCK; } /* - * Mark the given slot is locked. The function must be called with - * mapping->tree_lock held + * Mark the given slot as locked. Must be called with the i_pages lock held. */ static inline void *lock_slot(struct address_space *mapping, void **slot) { unsigned long entry = (unsigned long) - radix_tree_deref_slot_protected(slot, &mapping->tree_lock); + radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); entry |= RADIX_DAX_ENTRY_LOCK; - radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); + radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry); return (void *)entry; } /* - * Mark the given slot is unlocked. The function must be called with - * mapping->tree_lock held + * Mark the given slot as unlocked. Must be called with the i_pages lock held. */ static inline void *unlock_slot(struct address_space *mapping, void **slot) { unsigned long entry = (unsigned long) - radix_tree_deref_slot_protected(slot, &mapping->tree_lock); + radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; - radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); + radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry); return (void *)entry; } @@ -228,7 +224,7 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot) * put_locked_mapping_entry() when he locked the entry and now wants to * unlock it. * - * The function must be called with mapping->tree_lock held. + * Must be called with the i_pages lock held. */ static void *get_unlocked_mapping_entry(struct address_space *mapping, pgoff_t index, void ***slotp) @@ -241,7 +237,7 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping, ewait.wait.func = wake_exceptional_entry_func; for (;;) { - entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, + entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot); if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) || @@ -254,10 +250,10 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping, wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key); prepare_to_wait_exclusive(wq, &ewait.wait, TASK_UNINTERRUPTIBLE); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); schedule(); finish_wait(wq, &ewait.wait); - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(&mapping->i_pages); } } @@ -266,15 +262,15 @@ static void dax_unlock_mapping_entry(struct address_space *mapping, { void *entry, **slot; - spin_lock_irq(&mapping->tree_lock); - entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); + xa_lock_irq(&mapping->i_pages); + entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot); if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) || !slot_locked(mapping, slot))) { - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); return; } unlock_slot(mapping, slot); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); dax_wake_mapping_entry_waiter(mapping, index, entry, false); } @@ -388,7 +384,7 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, void *entry, **slot; restart: - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(&mapping->i_pages); entry = get_unlocked_mapping_entry(mapping, index, &slot); if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) { @@ -420,12 +416,12 @@ restart: if (pmd_downgrade) { /* * Make sure 'entry' remains valid while we drop - * mapping->tree_lock. + * the i_pages lock. */ entry = lock_slot(mapping, slot); } - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); /* * Besides huge zero pages the only other thing that gets * downgraded are empty entries which don't need to be @@ -442,27 +438,27 @@ restart: put_locked_mapping_entry(mapping, index); return ERR_PTR(err); } - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(&mapping->i_pages); if (!entry) { /* - * We needed to drop the page_tree lock while calling + * We needed to drop the i_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->page_tree, index, + entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot); if (entry) { radix_tree_preload_end(); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); goto restart; } } if (pmd_downgrade) { dax_disassociate_entry(entry, mapping, false); - radix_tree_delete(&mapping->page_tree, index); + radix_tree_delete(&mapping->i_pages, index); mapping->nrexceptional--; dax_wake_mapping_entry_waiter(mapping, index, entry, true); @@ -470,11 +466,11 @@ restart: entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY); - err = __radix_tree_insert(&mapping->page_tree, index, + err = __radix_tree_insert(&mapping->i_pages, index, dax_radix_order(entry), entry); radix_tree_preload_end(); if (err) { - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); /* * Our insertion of a DAX entry failed, most likely * because we were inserting a PMD entry and it @@ -487,12 +483,12 @@ restart: } /* Good, we have inserted empty locked entry into the tree. */ mapping->nrexceptional++; - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); return entry; } entry = lock_slot(mapping, slot); out_unlock: - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); return entry; } @@ -501,23 +497,23 @@ static int __dax_invalidate_mapping_entry(struct address_space *mapping, { int ret = 0; void *entry; - struct radix_tree_root *page_tree = &mapping->page_tree; + struct radix_tree_root *pages = &mapping->i_pages; - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(pages); entry = get_unlocked_mapping_entry(mapping, index, NULL); if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry))) goto out; if (!trunc && - (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || - radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))) + (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) || + radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE))) goto out; dax_disassociate_entry(entry, mapping, trunc); - radix_tree_delete(page_tree, index); + radix_tree_delete(pages, index); mapping->nrexceptional--; ret = 1; out: put_unlocked_mapping_entry(mapping, index, entry); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(pages); return ret; } /* @@ -587,7 +583,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, void *entry, pfn_t pfn_t, unsigned long flags, bool dirty) { - struct radix_tree_root *page_tree = &mapping->page_tree; + struct radix_tree_root *pages = &mapping->i_pages; unsigned long pfn = pfn_t_to_pfn(pfn_t); pgoff_t index = vmf->pgoff; void *new_entry; @@ -604,7 +600,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, unmap_mapping_pages(mapping, vmf->pgoff, 1, false); } - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(pages); new_entry = dax_radix_locked_entry(pfn, flags); if (dax_entry_size(entry) != dax_entry_size(new_entry)) { dax_disassociate_entry(entry, mapping, false); @@ -624,17 +620,17 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, void **slot; void *ret; - ret = __radix_tree_lookup(page_tree, index, &node, &slot); + ret = __radix_tree_lookup(pages, index, &node, &slot); WARN_ON_ONCE(ret != entry); - __radix_tree_replace(page_tree, node, slot, + __radix_tree_replace(pages, node, slot, new_entry, NULL); entry = new_entry; } if (dirty) - radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); + radix_tree_tag_set(pages, index, PAGECACHE_TAG_DIRTY); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(pages); return entry; } @@ -723,7 +719,7 @@ unlock_pte: 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; + struct radix_tree_root *pages = &mapping->i_pages; void *entry2, **slot; unsigned long pfn; long ret = 0; @@ -736,7 +732,7 @@ static int dax_writeback_one(struct dax_device *dax_dev, if (WARN_ON(!radix_tree_exceptional_entry(entry))) return -EIO; - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(pages); entry2 = get_unlocked_mapping_entry(mapping, index, &slot); /* Entry got punched out / reallocated? */ if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2))) @@ -755,7 +751,7 @@ static int dax_writeback_one(struct dax_device *dax_dev, } /* Another fsync thread may have already written back this entry */ - if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) + if (!radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE)) goto put_unlocked; /* Lock the entry to serialize with page faults */ entry = lock_slot(mapping, slot); @@ -763,11 +759,11 @@ static int dax_writeback_one(struct dax_device *dax_dev, * We can clear the tag now but we have to be careful so that concurrent * dax_writeback_one() calls for the same index cannot finish before we * actually flush the caches. This is achieved as the calls will look - * at the entry only under tree_lock and once they do that they will - * see the entry locked and wait for it to unlock. + * at the entry only under the i_pages lock and once they do that + * they will see the entry locked and wait for it to unlock. */ - radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); - spin_unlock_irq(&mapping->tree_lock); + radix_tree_tag_clear(pages, index, PAGECACHE_TAG_TOWRITE); + xa_unlock_irq(pages); /* * Even if dax_writeback_mapping_range() was given a wbc->range_start @@ -787,16 +783,16 @@ static int dax_writeback_one(struct dax_device *dax_dev, * the pfn mappings are writeprotected and fault waits for mapping * entry lock. */ - spin_lock_irq(&mapping->tree_lock); - radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY); - spin_unlock_irq(&mapping->tree_lock); + xa_lock_irq(pages); + radix_tree_tag_clear(pages, index, PAGECACHE_TAG_DIRTY); + xa_unlock_irq(pages); trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT); put_locked_mapping_entry(mapping, index); return ret; put_unlocked: put_unlocked_mapping_entry(mapping, index, entry2); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(pages); return ret; } @@ -1566,21 +1562,21 @@ static int dax_insert_pfn_mkwrite(struct vm_fault *vmf, pgoff_t index = vmf->pgoff; int vmf_ret, error; - spin_lock_irq(&mapping->tree_lock); + xa_lock_irq(&mapping->i_pages); entry = get_unlocked_mapping_entry(mapping, index, &slot); /* Did we race with someone splitting entry or so? */ if (!entry || (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) || (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) { put_unlocked_mapping_entry(mapping, index, entry); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf, VM_FAULT_NOPAGE); return VM_FAULT_NOPAGE; } - radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY); + radix_tree_tag_set(&mapping->i_pages, index, PAGECACHE_TAG_DIRTY); entry = lock_slot(mapping, slot); - spin_unlock_irq(&mapping->tree_lock); + xa_unlock_irq(&mapping->i_pages); switch (pe_size) { case PE_SIZE_PTE: error = vm_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); -- cgit v1.2.3-55-g7522