f2fs: use iomap for direct I/O

Make f2fs_file_read_iter() and f2fs_file_write_iter() use the iomap
direct I/O implementation instead of the fs/direct-io.c one.

The iomap implementation is more efficient, and it also avoids the need
to add new features and optimizations to the old implementation.

This new implementation also eliminates the need for f2fs to hook bio
submission and completion and to allocate memory per-bio.  This is
because it's possible to correctly update f2fs's in-flight DIO counters
using __iomap_dio_rw() in combination with an implementation of
iomap_dio_ops::end_io() (as suggested by Christoph Hellwig).

When possible, this new implementation preserves existing f2fs behavior
such as the conditions for falling back to buffered I/O.

This patch has been tested with xfstests by running 'gce-xfstests -c
f2fs -g auto -X generic/017' with and without this patch; no regressions
were seen.  (Some tests fail both before and after.  generic/017 hangs
both before and after, so it had to be excluded.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
[Jaegeuk Kim: use spin_lock_bh for f2fs_update_iostat in softirq]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 1 insertions, 7 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 8242f47304a5..ac6dda6c4c5a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1807,13 +1807,6 @@ struct f2fs_sb_info {
 #endif
 };
 
-struct f2fs_private_dio {
-	struct inode *inode;
-	void *orig_private;
-	bio_end_io_t *orig_end_io;
-	bool write;
-};
-
 #ifdef CONFIG_F2FS_FAULT_INJECTION
 #define f2fs_show_injection_info(sbi, type)					\
 	printk_ratelimited("%sF2FS-fs (%s) : inject %s in %s of %pS\n",	\
@@ -3642,6 +3635,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 				struct writeback_control *wbc,
 				enum iostat_type io_type,
 				int compr_blocks, bool allow_balance);
+void f2fs_write_failed(struct inode *inode, loff_t to);
 void f2fs_invalidate_page(struct page *page, unsigned int offset,
 			unsigned int length);
 int f2fs_release_page(struct page *page, gfp_t wait);