From: Kent Overstreet <kent.overstreet@gmail.com>
Date: Sat, 18 Jun 2022 22:33:25 +0000 (-0400)
Subject: cmd_dump: Use buffered IO for reading device metadata
X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=03b8098d370c864422527024b24dd2c9339c74db;p=bcachefs-tools-debian

cmd_dump: Use buffered IO for reading device metadata

We're reading device metadat in mostly sequential order - buffered IO
will be faster than O_DIRECT.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
---

diff --git a/cmd_dump.c b/cmd_dump.c
index 895e0cd..39d28f2 100644
--- a/cmd_dump.c
+++ b/cmd_dump.c
@@ -99,7 +99,7 @@ static void dump_one_device(struct bch_fs *c, struct bch_dev *ca, int fd,
 		bch2_trans_exit(&trans);
 	}
 
-	qcow2_write_image(ca->disk_sb.bdev->bd_fd, fd, &data,
+	qcow2_write_image(ca->disk_sb.bdev->bd_buffered_fd, fd, &data,
 			  max_t(unsigned, btree_bytes(c) / 8, block_bytes(c)));
 	darray_exit(&data);
 }
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 2d137e5..22bae25 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -40,6 +40,7 @@ struct block_device {
 	struct gendisk		__bd_disk;
 	int			bd_fd;
 	int			bd_sync_fd;
+	int			bd_buffered_fd;
 };
 
 #define bdev_kobj(_bdev) (&((_bdev)->kobj))
diff --git a/linux/blkdev.c b/linux/blkdev.c
index 762e5aa..b545e95 100644
--- a/linux/blkdev.c
+++ b/linux/blkdev.c
@@ -168,7 +168,7 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
 					void *holder)
 {
 	struct block_device *bdev;
-	int fd, sync_fd, flags = O_DIRECT;
+	int fd, sync_fd, buffered_fd, flags = 0;
 
 	if ((mode & (FMODE_READ|FMODE_WRITE)) == (FMODE_READ|FMODE_WRITE))
 		flags = O_RDWR;
@@ -183,16 +183,12 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
 		flags |= O_EXCL;
 #endif
 
-	fd = open(path, flags);
+	fd = open(path, flags|O_DIRECT);
 	if (fd < 0)
 		return ERR_PTR(-errno);
 
-	sync_fd = open(path, flags|O_SYNC);
-	if (sync_fd < 0) {
-		assert(0);
-		close(fd);
-		return ERR_PTR(-errno);
-	}
+	sync_fd	= xopen(path, flags|O_DIRECT|O_SYNC);
+	buffered_fd = xopen(path, flags);
 
 	bdev = malloc(sizeof(*bdev));
 	memset(bdev, 0, sizeof(*bdev));
@@ -203,6 +199,7 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
 	bdev->bd_dev		= xfstat(fd).st_rdev;
 	bdev->bd_fd		= fd;
 	bdev->bd_sync_fd	= sync_fd;
+	bdev->bd_buffered_fd	= buffered_fd;
 	bdev->bd_holder		= holder;
 	bdev->bd_disk		= &bdev->__bd_disk;
 	bdev->bd_disk->bdi	= &bdev->bd_disk->__bdi;