[RFC PATCH V12 10/14] Btrfs: subpagesize-blocksize: btrfs_punch_hole: Use EXTENT_UPTODATE bit to check for the presence of block in page cache

[Chandan Rajendra <chandan@linux.vnet.ibm.com>]

In subpagesize-blocksize, we have multiple blocks in a page. Checking for
existence of a page in the page cache isn't a sufficient check, since we could
be truncating a subset of the blocks mapped by the page. So if the blocks that
are neighboring the truncated block exist in the page cache,
btrfs_page_exists_in_range() would always return 1. Hence check for the
existence of EXTENT_UPTODATE bit on the file range mapped by the block being
punched out.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
 fs/btrfs/btrfs_inode.h | 2 --
 fs/btrfs/file.c        | 4 +++-
 fs/btrfs/inode.c       | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 0ef5cc1..2bf8043 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -323,6 +323,4 @@ static inline void btrfs_inode_resume_unlocked_dio(struct inode *inode)
 		  &BTRFS_I(inode)->runtime_flags);
 }
 
-bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end);
-
 #endif
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 386299f..2c0fd01 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2439,7 +2439,9 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		if ((!ordered ||
 		    (ordered->file_offset + ordered->len <= lockstart ||
 		     ordered->file_offset > lockend)) &&
-		     !btrfs_page_exists_in_range(inode, lockstart, lockend)) {
+		     !test_range_bit(&BTRFS_I(inode)->io_tree, lockstart,
+				     lockend, EXTENT_UPTODATE, 0,
+				     cached_state)) {
 			if (ordered)
 				btrfs_put_ordered_extent(ordered);
 			break;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fea4693..bd96bac 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7434,7 +7434,8 @@ out:
 	return ret;
 }
 
-bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end)
+static bool btrfs_page_exists_in_range(struct inode *inode, loff_t start,
+				loff_t end)
 {
 	struct radix_tree_root *root = &inode->i_mapping->page_tree;
 	int found = false;
-- 
2.1.0