f2fs: support multiple devices

This patch implements multiple devices support for f2fs.
Given multiple devices by mkfs.f2fs, f2fs shows them entirely as one big
volume under one f2fs instance.

Internal block management is very simple, but we will modify block allocation
and background GC policy to boost IO speed by exploiting them accoording to
each device speed.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 48 insertions, 7 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 996b9aef94ce..861173f00459 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -88,6 +88,46 @@ static void f2fs_write_end_io(struct bio *bio)
 }
 
 /*
+ * Return true, if pre_bio's bdev is same as its target device.
+ */
+struct block_device *f2fs_target_device(struct f2fs_sb_info *sbi,
+				block_t blk_addr, struct bio *bio)
+{
+	struct block_device *bdev = sbi->sb->s_bdev;
+	int i;
+
+	for (i = 0; i < sbi->s_ndevs; i++) {
+		if (FDEV(i).start_blk <= blk_addr &&
+					FDEV(i).end_blk >= blk_addr) {
+			blk_addr -= FDEV(i).start_blk;
+			bdev = FDEV(i).bdev;
+			break;
+		}
+	}
+	if (bio) {
+		bio->bi_bdev = bdev;
+		bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
+	}
+	return bdev;
+}
+
+int f2fs_target_device_index(struct f2fs_sb_info *sbi, block_t blkaddr)
+{
+	int i;
+
+	for (i = 0; i < sbi->s_ndevs; i++)
+		if (FDEV(i).start_blk <= blkaddr && FDEV(i).end_blk >= blkaddr)
+			return i;
+	return 0;
+}
+
+static bool __same_bdev(struct f2fs_sb_info *sbi,
+				block_t blk_addr, struct bio *bio)
+{
+	return f2fs_target_device(sbi, blk_addr, NULL) == bio->bi_bdev;
+}
+
+/*
  * Low-level block read/write IO operations.
  */
 static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
@@ -97,8 +137,7 @@ static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
 
 	bio = f2fs_bio_alloc(npages);
 
-	bio->bi_bdev = sbi->sb->s_bdev;
-	bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
+	f2fs_target_device(sbi, blk_addr, bio);
 	bio->bi_end_io = is_read ? f2fs_read_end_io : f2fs_write_end_io;
 	bio->bi_private = is_read ? NULL : sbi;
 
@@ -273,7 +312,8 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
 	down_write(&io->io_rwsem);
 
 	if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 ||
-	    (io->fio.op != fio->op || io->fio.op_flags != fio->op_flags)))
+	    (io->fio.op != fio->op || io->fio.op_flags != fio->op_flags) ||
+			!__same_bdev(sbi, fio->new_blkaddr, io->bio)))
 		__submit_merged_bio(io);
 alloc_new:
 	if (io->bio == NULL) {
@@ -961,7 +1001,6 @@ static struct bio *f2fs_grab_bio(struct inode *inode, block_t blkaddr,
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct fscrypt_ctx *ctx = NULL;
-	struct block_device *bdev = sbi->sb->s_bdev;
 	struct bio *bio;
 
 	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
@@ -979,8 +1018,7 @@ static struct bio *f2fs_grab_bio(struct inode *inode, block_t blkaddr,
 			fscrypt_release_ctx(ctx);
 		return ERR_PTR(-ENOMEM);
 	}
-	bio->bi_bdev = bdev;
-	bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blkaddr);
+	f2fs_target_device(sbi, blkaddr, bio);
 	bio->bi_end_io = f2fs_read_end_io;
 	bio->bi_private = ctx;
 
@@ -1075,7 +1113,8 @@ got_it:
 		 * This page will go to BIO.  Do we need to send this
 		 * BIO off first?
 		 */
-		if (bio && (last_block_in_bio != block_nr - 1)) {
+		if (bio && (last_block_in_bio != block_nr - 1 ||
+			!__same_bdev(F2FS_I_SB(inode), block_nr, bio))) {
 submit_and_realloc:
 			__submit_bio(F2FS_I_SB(inode), bio, DATA);
 			bio = NULL;
@@ -1734,6 +1773,8 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 		return 0;
 	if (rw == WRITE && test_opt(F2FS_I_SB(inode), LFS))
 		return 0;
+	if (F2FS_I_SB(inode)->s_ndevs)
+		return 0;
 
 	trace_f2fs_direct_IO_enter(inode, offset, count, rw);