[PATCH 01/18] fs: factor out a __generic_write_end helper

Christoph Hellwig
2018-05-30T10:00:22Z

Bits of the buffer.c based write_end implementations that don't know
about buffer_heads and can be reused by other implementations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/buffer.c | 67 +++++++++++++++++++++++++++------------------------
fs/internal.h | 2 ++
2 files changed, 37 insertions(+), 32 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 249b83fafe48..bd964b2ad99a 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2076,6 +2076,40 @@ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
}
EXPORT_SYMBOL(block_write_begin);

+int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
+ struct page *page)
+{
+ loff_t old_size = inode->i_size;
+ bool i_size_changed = false;
+
+ /*
+ * No need to use i_size_read() here, the i_size cannot change under us
+ * because we hold i_rwsem.
+ *
+ * But it's important to update i_size while still holding page lock:
+ * page writeout could otherwise come in and zero beyond i_size.
+ */
+ if (pos + copied > inode->i_size) {
+ i_size_write(inode, pos + copied);
+ i_size_changed = true;
+ }
+
+ unlock_page(page);
+ put_page(page);
+
+ if (old_size < pos)
+ pagecache_isize_extended(inode, old_size, pos);
+ /*
+ * Don't mark the inode dirty under page lock. First, it unnecessarily
+ * makes the holding time of page lock longer. Second, it forces lock
+ * ordering of page lock and transaction start for journaling
+ * filesystems.
+ */
+ if (i_size_changed)
+ mark_inode_dirty(inode);
+ return copied;
+}
+
int block_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
@@ -2116,39 +2150,8 @@ int generic_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
- struct inode *inode = mapping->host;
- loff_t old_size = inode->i_size;
- int i_size_changed = 0;
-
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
-
- /*
- * No need to use i_size_read() here, the i_size
- * cannot change under us because we hold i_mutex.
- *
- * But it's important to update i_size while still holding page lock:
- * page writeout could otherwise come in and zero beyond i_size.
- */
- if (pos+copied > inode->i_size) {
- i_size_write(inode, pos+copied);
- i_size_changed = 1;
- }
-
- unlock_page(page);
- put_page(page);
-
- if (old_size < pos)
- pagecache_isize_extended(inode, old_size, pos);
- /*
- * Don't mark the inode dirty under page lock. First, it unnecessarily
- * makes the holding time of page lock longer. Second, it forces lock
- * ordering of page lock and transaction start for journaling
- * filesystems.
- */
- if (i_size_changed)
- mark_inode_dirty(inode);
-
- return copied;
+ return __generic_write_end(mapping->host, pos, copied, page);
}
EXPORT_SYMBOL(generic_write_end);

diff --git a/fs/internal.h b/fs/internal.h
index e08972db0303..b955232d3d49 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -43,6 +43,8 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait)
extern void guard_bio_eod(int rw, struct bio *bio);
extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
get_block_t *get_block, struct iomap *iomap);
+int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
+ struct page *page);

/*
* char_dev.c
--
2.17.0