From da2c7009f6cafe0a550cf57a1aa79e0f1b3093d6 Mon Sep 17 00:00:00 2001
From: Liu Bo <bo.li.liu@oracle.com>
Date: Fri, 10 Feb 2017 16:41:05 +0100
Subject: [PATCH] btrfs: teach __process_pages_contig about PAGE_LOCK operation
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ changes to the helper separated from the following patch ]
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/extent_io.c | 48 ++++++++++++++++++++++++++++++++++++++------
fs/btrfs/extent_io.h | 3 ++-
2 files changed, 44 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 664f52c1c58aa..5bb7ced206950 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1554,6 +1554,11 @@ out:
return found;
}
+static int __process_pages_contig(struct address_space *mapping,
+ struct page *locked_page,
+ pgoff_t start_index, pgoff_t end_index,
+ unsigned long page_ops, pgoff_t *index_ret);
+
static noinline void __unlock_for_delalloc(struct inode *inode,
struct page *locked_page,
u64 start, u64 end)
@@ -1731,17 +1736,24 @@ out_failed:
return found;
}
-static void __process_pages_contig(struct address_space *mapping,
- struct page *locked_page,
- pgoff_t start_index, pgoff_t end_index,
- unsigned long page_ops)
+static int __process_pages_contig(struct address_space *mapping,
+ struct page *locked_page,
+ pgoff_t start_index, pgoff_t end_index,
+ unsigned long page_ops, pgoff_t *index_ret)
{
unsigned long nr_pages = end_index - start_index + 1;
+ unsigned long pages_locked = 0;
pgoff_t index = start_index;
struct page *pages[16];
unsigned ret;
+ int err = 0;
int i;
+ if (page_ops & PAGE_LOCK) {
+ ASSERT(page_ops == PAGE_LOCK);
+ ASSERT(index_ret && *index_ret == start_index);
+ }
+
if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
mapping_set_error(mapping, -EIO);
@@ -1749,13 +1761,22 @@ static void __process_pages_contig(struct address_space *mapping,
ret = find_get_pages_contig(mapping, index,
min_t(unsigned long,
nr_pages, ARRAY_SIZE(pages)), pages);
- for (i = 0; i < ret; i++) {
+ if (ret == 0) {
+ /*
+ * Only if we're going to lock these pages,
+ * can we find nothing at @index.
+ */
+ ASSERT(page_ops & PAGE_LOCK);
+ return ret;
+ }
+ for (i = 0; i < ret; i++) {
if (page_ops & PAGE_SET_PRIVATE2)
SetPagePrivate2(pages[i]);
if (pages[i] == locked_page) {
put_page(pages[i]);
+ pages_locked++;
continue;
}
if (page_ops & PAGE_CLEAR_DIRTY)
@@ -1768,12 +1789,27 @@ static void __process_pages_contig(struct address_space *mapping,
end_page_writeback(pages[i]);
if (page_ops & PAGE_UNLOCK)
unlock_page(pages[i]);
+ if (page_ops & PAGE_LOCK) {
+ lock_page(pages[i]);
+ if (!PageDirty(pages[i]) ||
+ pages[i]->mapping != mapping) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ err = -EAGAIN;
+ goto out;
+ }
+ }
put_page(pages[i]);
+ pages_locked++;
}
nr_pages -= ret;
index += ret;
cond_resched();
}
+out:
+ if (err && index_ret)
+ *index_ret = start_index + pages_locked - 1;
+ return err;
}
void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
@@ -1786,7 +1822,7 @@ void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
__process_pages_contig(inode->i_mapping, locked_page,
start >> PAGE_SHIFT, end >> PAGE_SHIFT,
- page_ops);
+ page_ops, NULL);
}
/*
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 17f9ce479ed7f..4551a5b4b8f59 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -45,13 +45,14 @@
#define EXTENT_BUFFER_IN_TREE 10
#define EXTENT_BUFFER_WRITE_ERR 11 /* write IO error */
-/* these are flags for extent_clear_unlock_delalloc */
+/* these are flags for __process_pages_contig */
#define PAGE_UNLOCK (1 << 0)
#define PAGE_CLEAR_DIRTY (1 << 1)
#define PAGE_SET_WRITEBACK (1 << 2)
#define PAGE_END_WRITEBACK (1 << 3)
#define PAGE_SET_PRIVATE2 (1 << 4)
#define PAGE_SET_ERROR (1 << 5)
+#define PAGE_LOCK (1 << 6)
/*
* page->private values. Every page that is controlled by the extent
--
2.30.2