From: Matthew Wilcox <willy@infradead.org>
To: unlisted-recipients:; (no To-header on input)
Cc: Matthew Wilcox <mawilcox@microsoft.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Jens Axboe <axboe@kernel.dk>, Rehas Sachdeva <aquannie@gmail.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org,
linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 22/73] page cache: Convert hole search to XArray
Date: Tue, 5 Dec 2017 16:41:08 -0800 [thread overview]
Message-ID: <20171206004159.3755-23-willy@infradead.org> (raw)
In-Reply-To: <20171206004159.3755-1-willy@infradead.org>
From: Matthew Wilcox <mawilcox@microsoft.com>
The page cache offers the ability to search for a miss in the previous or
next N locations. Rather than teach the XArray about the page cache's
definition of a miss, use xas_prev() and xas_next() to search the page
array. This should be more efficient as it does not have to start the
lookup from the top for each index.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
fs/nfs/blocklayout/blocklayout.c | 2 +-
include/linux/pagemap.h | 4 +-
mm/filemap.c | 110 ++++++++++++++++++---------------------
mm/readahead.c | 4 +-
4 files changed, 55 insertions(+), 65 deletions(-)
diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 995d707537da..7bd643538cff 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -826,7 +826,7 @@ static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx)
end = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
if (end != inode->i_mapping->nrpages) {
rcu_read_lock();
- end = page_cache_next_hole(mapping, idx + 1, ULONG_MAX);
+ end = page_cache_next_gap(mapping, idx + 1, ULONG_MAX);
rcu_read_unlock();
}
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 80a6149152d4..0db127c3ccac 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -241,9 +241,9 @@ static inline gfp_t readahead_gfp_mask(struct address_space *x)
typedef int filler_t(void *, struct page *);
-pgoff_t page_cache_next_hole(struct address_space *mapping,
+pgoff_t page_cache_next_gap(struct address_space *mapping,
pgoff_t index, unsigned long max_scan);
-pgoff_t page_cache_prev_hole(struct address_space *mapping,
+pgoff_t page_cache_prev_gap(struct address_space *mapping,
pgoff_t index, unsigned long max_scan);
#define FGP_ACCESSED 0x00000001
diff --git a/mm/filemap.c b/mm/filemap.c
index 1d012dd3629e..650624f7b79d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1326,86 +1326,76 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
}
/**
- * page_cache_next_hole - find the next hole (not-present entry)
- * @mapping: mapping
- * @index: index
- * @max_scan: maximum range to search
- *
- * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
- * lowest indexed hole.
- *
- * Returns: the index of the hole if found, otherwise returns an index
- * outside of the set specified (in which case 'return - index >=
- * max_scan' will be true). In rare cases of index wrap-around, 0 will
- * be returned.
- *
- * page_cache_next_hole may be called under rcu_read_lock. However,
- * like radix_tree_gang_lookup, this will not atomically search a
- * snapshot of the tree at a single point in time. For example, if a
- * hole is created at index 5, then subsequently a hole is created at
- * index 10, page_cache_next_hole covering both indexes may return 10
- * if called under rcu_read_lock.
+ * page_cache_next_gap() - Find the next gap in the page cache.
+ * @mapping: Mapping.
+ * @index: Index.
+ * @max_scan: Maximum range to search.
+ *
+ * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
+ * gap with the lowest index.
+ *
+ * This function may be called under the rcu_read_lock. However, this will
+ * not atomically search a snapshot of the cache at a single point in time.
+ * For example, if a gap is created at index 5, then subsequently a gap is
+ * created at index 10, page_cache_next_gap covering both indices may
+ * return 10 if called under the rcu_read_lock.
+ *
+ * Return: The index of the gap if found, otherwise an index outside the
+ * range specified (in which case 'return - index >= max_scan' will be true).
+ * In the rare case of index wrap-around, 0 will be returned.
*/
-pgoff_t page_cache_next_hole(struct address_space *mapping,
+pgoff_t page_cache_next_gap(struct address_space *mapping,
pgoff_t index, unsigned long max_scan)
{
- unsigned long i;
+ XA_STATE(xas, &mapping->pages, index);
- for (i = 0; i < max_scan; i++) {
- struct page *page;
-
- page = radix_tree_lookup(&mapping->pages, index);
- if (!page || xa_is_value(page))
+ while (max_scan--) {
+ void *entry = xas_next(&xas);
+ if (!entry || xa_is_value(entry))
break;
- index++;
- if (index == 0)
+ if (xas.xa_index == 0)
break;
}
- return index;
+ return xas.xa_index;
}
-EXPORT_SYMBOL(page_cache_next_hole);
+EXPORT_SYMBOL(page_cache_next_gap);
/**
- * page_cache_prev_hole - find the prev hole (not-present entry)
- * @mapping: mapping
- * @index: index
- * @max_scan: maximum range to search
- *
- * Search backwards in the range [max(index-max_scan+1, 0), index] for
- * the first hole.
- *
- * Returns: the index of the hole if found, otherwise returns an index
- * outside of the set specified (in which case 'index - return >=
- * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX
- * will be returned.
- *
- * page_cache_prev_hole may be called under rcu_read_lock. However,
- * like radix_tree_gang_lookup, this will not atomically search a
- * snapshot of the tree at a single point in time. For example, if a
- * hole is created at index 10, then subsequently a hole is created at
- * index 5, page_cache_prev_hole covering both indexes may return 5 if
- * called under rcu_read_lock.
+ * page_cache_prev_gap() - Find the next gap in the page cache.
+ * @mapping: Mapping.
+ * @index: Index.
+ * @max_scan: Maximum range to search.
+ *
+ * Search the range [max(index - max_scan + 1, 0), index] for the
+ * gap with the highest index.
+ *
+ * This function may be called under the rcu_read_lock. However, this will
+ * not atomically search a snapshot of the cache at a single point in time.
+ * For example, if a gap is created at index 10, then subsequently a gap is
+ * created at index 5, page_cache_prev_gap() covering both indices may
+ * return 5 if called under the rcu_read_lock.
+ *
+ * Return: The index of the gap if found, otherwise an index outside the
+ * range specified (in which case 'index - return >= max_scan' will be true).
+ * In the rare case of wrap-around, ULONG_MAX will be returned.
*/
-pgoff_t page_cache_prev_hole(struct address_space *mapping,
+pgoff_t page_cache_prev_gap(struct address_space *mapping,
pgoff_t index, unsigned long max_scan)
{
- unsigned long i;
-
- for (i = 0; i < max_scan; i++) {
- struct page *page;
+ XA_STATE(xas, &mapping->pages, index);
- page = radix_tree_lookup(&mapping->pages, index);
- if (!page || xa_is_value(page))
+ while (max_scan--) {
+ void *entry = xas_prev(&xas);
+ if (!entry || xa_is_value(entry))
break;
- index--;
- if (index == ULONG_MAX)
+ if (xas.xa_index == ULONG_MAX)
break;
}
- return index;
+ return xas.xa_index;
}
-EXPORT_SYMBOL(page_cache_prev_hole);
+EXPORT_SYMBOL(page_cache_prev_gap);
/**
* find_get_entry - find and get a page cache entry
diff --git a/mm/readahead.c b/mm/readahead.c
index 4851f002605f..f64b31b3a84a 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -329,7 +329,7 @@ static pgoff_t count_history_pages(struct address_space *mapping,
pgoff_t head;
rcu_read_lock();
- head = page_cache_prev_hole(mapping, offset - 1, max);
+ head = page_cache_prev_gap(mapping, offset - 1, max);
rcu_read_unlock();
return offset - 1 - head;
@@ -417,7 +417,7 @@ ondemand_readahead(struct address_space *mapping,
pgoff_t start;
rcu_read_lock();
- start = page_cache_next_hole(mapping, offset + 1, max_pages);
+ start = page_cache_next_gap(mapping, offset + 1, max_pages);
rcu_read_unlock();
if (!start || start - offset > max_pages)
--
2.15.0
next prev parent reply other threads:[~2017-12-06 0:42 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-06 0:40 [PATCH v4 00/73] XArray version 4 Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 01/73] xfs: Rename xa_ elements to ail_ Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 02/73] xarray: Add the xa_lock to the radix_tree_root Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 03/73] page cache: Use xa_lock Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 04/73] xarray: Replace exceptional entries Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 05/73] xarray: Change definition of sibling entries Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 06/73] xarray: Add definition of struct xarray Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 07/73] xarray: Define struct xa_node Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 08/73] xarray: Add documentation Matthew Wilcox
2017-12-11 23:10 ` Randy Dunlap
2017-12-15 4:22 ` Matthew Wilcox
2017-12-15 12:34 ` Naming of tag operations in the XArray Matthew Wilcox
2017-12-19 0:16 ` Randy Dunlap
2017-12-15 17:10 ` Storing errors " Matthew Wilcox
2017-12-19 0:27 ` Randy Dunlap
2017-12-06 0:40 ` [PATCH v4 09/73] xarray: Add xa_load Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 10/73] xarray: Add xa_get_tag, xa_set_tag and xa_clear_tag Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 11/73] xarray: Add xa_store Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 12/73] xarray: Add xa_cmpxchg Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 13/73] xarray: Add xa_for_each Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 14/73] xarray: Add xas_for_each_tag Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 15/73] xarray: Add xa_get_entries, xa_get_tagged and xa_get_maybe_tag Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 16/73] xarray: Add xa_destroy Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 17/73] xarray: Add xas_next and xas_prev Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 18/73] xarray: Add xas_create_range Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 19/73] xarray: Add MAINTAINERS entry Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 20/73] idr: Convert to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 21/73] ida: " Matthew Wilcox
2017-12-06 0:41 ` Matthew Wilcox [this message]
2017-12-06 0:41 ` [PATCH v4 23/73] page cache: Add page_cache_range_empty function Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 24/73] page cache: Add and replace pages using the XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 25/73] page cache: Convert page deletion to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 26/73] page cache: Convert page cache lookups " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 27/73] page cache: Convert delete_batch " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 28/73] page cache: Remove stray radix comment Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 29/73] mm: Convert page-writeback to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 30/73] mm: Convert workingset " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 31/73] mm: Convert truncate " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 32/73] mm: Convert add_to_swap_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 33/73] mm: Convert delete_from_swap_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 34/73] mm: Convert cgroup writeback " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 35/73] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 36/73] mm: Convert page migration " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 37/73] mm: Convert huge_memory " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 38/73] mm: Convert collapse_shmem " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 39/73] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 40/73] pagevec: Use xa_tag_t Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 41/73] shmem: Convert replace to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 42/73] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 43/73] shmem: Convert find_swap_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 44/73] shmem: Convert shmem_tag_pins " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 45/73] shmem: Convert shmem_wait_for_pins " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 46/73] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 47/73] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 48/73] shmem: Convert shmem_free_swap " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 49/73] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 50/73] shmem: Comment fixups Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 51/73] btrfs: Convert page cache to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 52/73] fs: Convert buffer " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 53/73] fs: Convert writeback " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 54/73] nilfs2: Convert " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 55/73] f2fs: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 56/73] lustre: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 57/73] dax: Convert dax_unlock_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 58/73] dax: Convert lock_slot " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 59/73] dax: More XArray conversion Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 60/73] dax: Convert __dax_invalidate_mapping_entry to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 61/73] dax: Convert dax_writeback_one " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 62/73] dax: Convert dax_insert_pfn_mkwrite " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 63/73] dax: Convert dax_insert_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 64/73] dax: Convert grab_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 65/73] dax: Fix sparse warning Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 66/73] page cache: Finish XArray conversion Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 67/73] vmalloc: Convert to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 68/73] brd: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 69/73] xfs: Convert m_perag_tree " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 70/73] xfs: Convert pag_ici_root " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 71/73] xfs: Convert xfs dquot " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 72/73] xfs: Convert mru cache " Matthew Wilcox
2017-12-06 1:36 ` Dave Chinner
2017-12-06 2:02 ` Matthew Wilcox
2017-12-06 3:14 ` Dave Chinner
2017-12-06 4:45 ` Matthew Wilcox
2017-12-06 4:52 ` Matthew Wilcox
2017-12-06 8:44 ` Dave Chinner
2017-12-06 14:06 ` Matthew Wilcox
2017-12-07 0:38 ` Dave Chinner
2017-12-08 23:01 ` Matthew Wilcox
2017-12-10 23:57 ` Dave Chinner
2017-12-11 4:23 ` Matthew Wilcox
2017-12-11 21:55 ` Dave Chinner
2017-12-07 16:06 ` Theodore Ts'o
2017-12-07 22:22 ` Dave Chinner
2017-12-08 4:45 ` Byungchul Park
2017-12-08 7:25 ` Dave Chinner
2017-12-08 9:27 ` Byungchul Park
2017-12-08 17:35 ` Alan Stern
2017-12-08 22:36 ` Dave Chinner
2017-12-09 17:00 ` Joe Perches
2017-12-11 21:43 ` Dave Chinner
2017-12-11 22:12 ` Joe Perches
2017-12-11 22:43 ` Matthew Wilcox
2017-12-11 23:46 ` Joe Perches
2017-12-12 15:51 ` Alan Stern
2017-12-14 18:23 ` Joe Perches
2017-12-17 1:26 ` [RFC patch] checkpatch: Add a test for long function definitions (>200 lines) Joe Perches
2017-12-17 21:46 ` Linus Torvalds
2017-12-17 22:22 ` Joe Perches
2017-12-17 22:33 ` Luc Van Oostenryck
2017-12-11 23:38 ` [PATCH v4 72/73] xfs: Convert mru cache to XArray Dave Chinner
2017-12-21 12:05 ` Knut Omang
2017-12-07 22:38 ` Lockdep is less useful than it was Matthew Wilcox
2017-12-07 22:39 ` Matthew Wilcox
2017-12-08 0:14 ` Dave Chinner
2017-12-08 15:27 ` Theodore Ts'o
2017-12-08 18:14 ` Matthew Wilcox
2017-12-08 22:47 ` Dave Chinner
2017-12-06 0:41 ` [PATCH v4 73/73] usb: Convert xhci-mem to XArray Matthew Wilcox
2017-12-06 1:45 ` [PATCH v4 00/73] XArray version 4 Dave Chinner
2017-12-06 1:51 ` Dave Chinner
2017-12-06 1:53 ` Matthew Wilcox
2017-12-06 2:17 ` Dave Chinner
2017-12-06 2:27 ` Matthew Wilcox
2017-12-06 2:05 ` Matthew Wilcox
2017-12-06 2:38 ` Dave Chinner
2017-12-06 23:58 ` Ross Zwisler
2017-12-07 0:13 ` Matthew Wilcox
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