fs: factor out a __generic_write_end helper

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>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

2 files changed, 37 insertions, 32 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index cabc045f483d..aba2a948b235 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 980d005b21b4..4a18bdbd2214 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