diff mbox series

[v2,1/2] filemap: find_lock_entries() now updates start offset

Message ID 20221013225708.1879-2-vishal.moola@gmail.com
State New
Headers
Series Rework find_get_entries() and find_lock_entries() |

Commit Message

Vishal Moola Oct. 13, 2022, 10:57 p.m. UTC 
  Initially, find_lock_entries() was being passed in the start offset as a
value. That left the calculation of the offset to the callers. This led
to complexity in the callers trying to keep track of the index.

Now find_lock_entires() takes in a pointer to the start offset and
updates the value to be directly after the last entry found. If no entry is
found, the offset is not changed. This gets rid of multiple hacky
calculations that kept track of the start offset.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 mm/filemap.c  | 17 +++++++++++++----
 mm/internal.h |  2 +-
 mm/shmem.c    |  8 ++------
 mm/truncate.c | 11 +++--------
 4 files changed, 19 insertions(+), 19 deletions(-)

Comments

Matthew Wilcox Oct. 14, 2022, 3:24 a.m. UTC | #1 
On Thu, Oct 13, 2022 at 03:57:07PM -0700, Vishal Moola (Oracle) wrote:
> Initially, find_lock_entries() was being passed in the start offset as a
> value. That left the calculation of the offset to the callers. This led
> to complexity in the callers trying to keep track of the index.
> 
> Now find_lock_entires() takes in a pointer to the start offset and

s/entires/entries/

> updates the value to be directly after the last entry found. If no entry is
> found, the offset is not changed. This gets rid of multiple hacky
> calculations that kept track of the start offset.

> @@ -2120,8 +2120,17 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
>  put:
>  		folio_put(folio);
>  	}
> -	rcu_read_unlock();
>  
> +	if (folio_batch_count(fbatch)) {
> +		unsigned long nr = 1;
> +		int idx = folio_batch_count(fbatch) - 1;
> +
> +		folio = fbatch->folios[idx];
> +		if (!xa_is_value(folio) && !folio_test_hugetlb(folio))
> +			nr = folio_nr_pages(folio);
> +		*start = indices[idx] + nr;
> +	}
> +	rcu_read_unlock();
>  	return folio_batch_count(fbatch);

Do we need to move the rcu_read_unlock()?  Pretty sure we can do all
these calculations without it.

This all looks good.  It's certainly more ergonomic to use.

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
diff mbox series

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index c943d1b90cc2..b6aaded95132 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2090,16 +2090,16 @@  unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
  *
  * Return: The number of entries which were found.
  */
-unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
+unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,
 		pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)
 {
-	XA_STATE(xas, &mapping->i_pages, start);
+	XA_STATE(xas, &mapping->i_pages, *start);
 	struct folio *folio;
 
 	rcu_read_lock();
 	while ((folio = find_get_entry(&xas, end, XA_PRESENT))) {
 		if (!xa_is_value(folio)) {
-			if (folio->index < start)
+			if (folio->index < *start)
 				goto put;
 			if (folio->index + folio_nr_pages(folio) - 1 > end)
 				goto put;
@@ -2120,8 +2120,17 @@  unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
 put:
 		folio_put(folio);
 	}
-	rcu_read_unlock();
 
+	if (folio_batch_count(fbatch)) {
+		unsigned long nr = 1;
+		int idx = folio_batch_count(fbatch) - 1;
+
+		folio = fbatch->folios[idx];
+		if (!xa_is_value(folio) && !folio_test_hugetlb(folio))
+			nr = folio_nr_pages(folio);
+		*start = indices[idx] + nr;
+	}
+	rcu_read_unlock();
 	return folio_batch_count(fbatch);
 }
 
diff --git a/mm/internal.h b/mm/internal.h
index 785409805ed7..14625de6714b 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -104,7 +104,7 @@  static inline void force_page_cache_readahead(struct address_space *mapping,
 	force_page_cache_ra(&ractl, nr_to_read);
 }
 
-unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
+unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,
 		pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices);
 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
 		pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices);
diff --git a/mm/shmem.c b/mm/shmem.c
index 42e5888bf84d..9e17a2b0dc43 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -932,21 +932,18 @@  static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 
 	folio_batch_init(&fbatch);
 	index = start;
-	while (index < end && find_lock_entries(mapping, index, end - 1,
+	while (index < end && find_lock_entries(mapping, &index, end - 1,
 			&fbatch, indices)) {
 		for (i = 0; i < folio_batch_count(&fbatch); i++) {
 			folio = fbatch.folios[i];
 
-			index = indices[i];
-
 			if (xa_is_value(folio)) {
 				if (unfalloc)
 					continue;
 				nr_swaps_freed += !shmem_free_swap(mapping,
-								index, folio);
+							indices[i], folio);
 				continue;
 			}
-			index += folio_nr_pages(folio) - 1;
 
 			if (!unfalloc || !folio_test_uptodate(folio))
 				truncate_inode_folio(mapping, folio);
@@ -955,7 +952,6 @@  static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 		folio_batch_remove_exceptionals(&fbatch);
 		folio_batch_release(&fbatch);
 		cond_resched();
-		index++;
 	}
 
 	same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
diff --git a/mm/truncate.c b/mm/truncate.c
index 0b0708bf935f..9fbe282e70ba 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -361,9 +361,8 @@  void truncate_inode_pages_range(struct address_space *mapping,
 
 	folio_batch_init(&fbatch);
 	index = start;
-	while (index < end && find_lock_entries(mapping, index, end - 1,
+	while (index < end && find_lock_entries(mapping, &index, end - 1,
 			&fbatch, indices)) {
-		index = indices[folio_batch_count(&fbatch) - 1] + 1;
 		truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
 		for (i = 0; i < folio_batch_count(&fbatch); i++)
 			truncate_cleanup_folio(fbatch.folios[i]);
@@ -510,20 +509,17 @@  unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
 	int i;
 
 	folio_batch_init(&fbatch);
-	while (find_lock_entries(mapping, index, end, &fbatch, indices)) {
+	while (find_lock_entries(mapping, &index, end, &fbatch, indices)) {
 		for (i = 0; i < folio_batch_count(&fbatch); i++) {
 			struct folio *folio = fbatch.folios[i];
 
 			/* We rely upon deletion not changing folio->index */
-			index = indices[i];
 
 			if (xa_is_value(folio)) {
 				count += invalidate_exceptional_entry(mapping,
-								      index,
-								      folio);
+							     indices[i], folio);
 				continue;
 			}
-			index += folio_nr_pages(folio) - 1;
 
 			ret = mapping_evict_folio(mapping, folio);
 			folio_unlock(folio);
@@ -542,7 +538,6 @@  unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
 		folio_batch_remove_exceptionals(&fbatch);
 		folio_batch_release(&fbatch);
 		cond_resched();
-		index++;
 	}
 	return count;
 }