btrfs: remove btrfs_bio::fs_info by extracting it from btrfs_bio::inode

Currently there is only one caller which doesn't populate
btrfs_bio::inode, and that's scrub.

The idea is scrub doesn't want any automatic csum verification nor
read-repair, as everything will be handled by scrub itself.

However that behavior is really no different than metadata inode, thus
we can reuse btree_inode as btrfs_bio::inode for scrub.

The only exception is in btrfs_submit_chunk() where if a bbio is from
scrub or data reloc inode, we set rst_search_commit_root to true.
This means we still need a way to distinguish scrub from metadata, but
that can be done by a new flag inside btrfs_bio.

Now btrfs_bio::inode is a mandatory parameter, we can extract fs_info
from that inode thus can remove btrfs_bio::fs_info to save 8 bytes from
btrfs_bio structure.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/bio.c

@@ -41,13 +41,17 @@ static bool bbio_has_ordered_extent(const struct btrfs_bio *bbio)
  * Initialize a btrfs_bio structure.  This skips the embedded bio itself as it
  * is already initialized by the block layer.
  */
-void btrfs_bio_init(struct btrfs_bio *bbio, struct btrfs_fs_info *fs_info,
+void btrfs_bio_init(struct btrfs_bio *bbio, struct btrfs_inode *inode, u64 file_offset,
 		    btrfs_bio_end_io_t end_io, void *private)
 {
+	/* @inode parameter is mandatory. */
+	ASSERT(inode);
+
 	memset(bbio, 0, offsetof(struct btrfs_bio, bio));
-	bbio->fs_info = fs_info;
+	bbio->inode = inode;
 	bbio->end_io = end_io;
 	bbio->private = private;
+	bbio->file_offset = file_offset;
 	atomic_set(&bbio->pending_ios, 1);
 	WRITE_ONCE(bbio->status, BLK_STS_OK);
 }
@@ -60,15 +64,15 @@ void btrfs_bio_init(struct btrfs_bio *bbio, struct btrfs_fs_info *fs_info,
  * a mempool.
  */
 struct btrfs_bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf,
-				  struct btrfs_fs_info *fs_info,
+				  struct btrfs_inode *inode, u64 file_offset,
 				  btrfs_bio_end_io_t end_io, void *private)
 {
 	struct btrfs_bio *bbio;
 	struct bio *bio;
 
 	bio = bio_alloc_bioset(NULL, nr_vecs, opf, GFP_NOFS, &btrfs_bioset);
 	bbio = btrfs_bio(bio);
-	btrfs_bio_init(bbio, fs_info, end_io, private);
+	btrfs_bio_init(bbio, inode, file_offset, end_io, private);
 	return bbio;
 }
 
@@ -85,9 +89,7 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info,
 		return ERR_CAST(bio);
 
 	bbio = btrfs_bio(bio);
-	btrfs_bio_init(bbio, fs_info, NULL, orig_bbio);
-	bbio->inode = orig_bbio->inode;
-	bbio->file_offset = orig_bbio->file_offset;
+	btrfs_bio_init(bbio, orig_bbio->inode, orig_bbio->file_offset, NULL, orig_bbio);
 	orig_bbio->file_offset += map_length;
 	if (bbio_has_ordered_extent(bbio)) {
 		refcount_inc(&orig_bbio->ordered->refs);
@@ -244,9 +246,8 @@ static struct btrfs_failed_bio *repair_one_sector(struct btrfs_bio *failed_bbio,
 	bio_add_folio_nofail(repair_bio, folio, sectorsize, foff);
 
 	repair_bbio = btrfs_bio(repair_bio);
-	btrfs_bio_init(repair_bbio, fs_info, NULL, fbio);
-	repair_bbio->inode = failed_bbio->inode;
-	repair_bbio->file_offset = failed_bbio->file_offset + bio_offset;
+	btrfs_bio_init(repair_bbio, failed_bbio->inode, failed_bbio->file_offset + bio_offset,
+		       NULL, fbio);
 
 	mirror = next_repair_mirror(fbio, failed_bbio->mirror_num);
 	btrfs_debug(fs_info, "submitting repair read to mirror %d", mirror);
@@ -332,7 +333,7 @@ static void btrfs_simple_end_io(struct bio *bio)
 {
 	struct btrfs_bio *bbio = btrfs_bio(bio);
 	struct btrfs_device *dev = bio->bi_private;
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 
 	btrfs_bio_counter_dec(fs_info);
 
@@ -581,10 +582,11 @@ static void run_one_async_done(struct btrfs_work *work, bool do_free)
 
 static bool should_async_write(struct btrfs_bio *bbio)
 {
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	bool auto_csum_mode = true;
 
 #ifdef CONFIG_BTRFS_EXPERIMENTAL
-	struct btrfs_fs_devices *fs_devices = bbio->fs_info->fs_devices;
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	enum btrfs_offload_csum_mode csum_mode = READ_ONCE(fs_devices->offload_csum_mode);
 
 	if (csum_mode == BTRFS_OFFLOAD_CSUM_FORCE_OFF)
@@ -594,7 +596,7 @@ static bool should_async_write(struct btrfs_bio *bbio)
 #endif
 
 	/* Submit synchronously if the checksum implementation is fast. */
-	if (auto_csum_mode && test_bit(BTRFS_FS_CSUM_IMPL_FAST, &bbio->fs_info->flags))
+	if (auto_csum_mode && test_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags))
 		return false;
 
 	/*
@@ -605,7 +607,7 @@ static bool should_async_write(struct btrfs_bio *bbio)
 		return false;
 
 	/* Zoned devices require I/O to be submitted in order. */
-	if ((bbio->bio.bi_opf & REQ_META) && btrfs_is_zoned(bbio->fs_info))
+	if ((bbio->bio.bi_opf & REQ_META) && btrfs_is_zoned(fs_info))
 		return false;
 
 	return true;
@@ -620,7 +622,7 @@ static bool btrfs_wq_submit_bio(struct btrfs_bio *bbio,
 				struct btrfs_io_context *bioc,
 				struct btrfs_io_stripe *smap, int mirror_num)
 {
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	struct async_submit_bio *async;
 
 	async = kmalloc(sizeof(*async), GFP_NOFS);
@@ -639,27 +641,28 @@ static bool btrfs_wq_submit_bio(struct btrfs_bio *bbio,
 
 static u64 btrfs_append_map_length(struct btrfs_bio *bbio, u64 map_length)
 {
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	unsigned int nr_segs;
 	int sector_offset;
 
-	map_length = min(map_length, bbio->fs_info->max_zone_append_size);
-	sector_offset = bio_split_rw_at(&bbio->bio, &bbio->fs_info->limits,
+	map_length = min(map_length, fs_info->max_zone_append_size);
+	sector_offset = bio_split_rw_at(&bbio->bio, &fs_info->limits,
 					&nr_segs, map_length);
 	if (sector_offset) {
 		/*
 		 * bio_split_rw_at() could split at a size smaller than our
 		 * sectorsize and thus cause unaligned I/Os.  Fix that by
 		 * always rounding down to the nearest boundary.
 		 */
-		return ALIGN_DOWN(sector_offset << SECTOR_SHIFT, bbio->fs_info->sectorsize);
+		return ALIGN_DOWN(sector_offset << SECTOR_SHIFT, fs_info->sectorsize);
 	}
 	return map_length;
 }
 
 static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 {
 	struct btrfs_inode *inode = bbio->inode;
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct bio *bio = &bbio->bio;
 	u64 logical = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 	u64 length = bio->bi_iter.bi_size;
@@ -670,7 +673,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 	blk_status_t status;
 	int ret;
 
-	if (!bbio->inode || btrfs_is_data_reloc_root(inode->root))
+	if (bbio->is_scrub || btrfs_is_data_reloc_root(inode->root))
 		smap.rst_search_commit_root = true;
 	else
 		smap.rst_search_commit_root = false;
@@ -782,7 +785,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 static void assert_bbio_alignment(struct btrfs_bio *bbio)
 {
 #ifdef CONFIG_BTRFS_ASSERT
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	struct bio_vec bvec;
 	struct bvec_iter iter;
 	const u32 blocksize = fs_info->sectorsize;
@@ -885,16 +888,16 @@ int btrfs_repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
  */
 void btrfs_submit_repair_write(struct btrfs_bio *bbio, int mirror_num, bool dev_replace)
 {
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	u64 logical = bbio->bio.bi_iter.bi_sector << SECTOR_SHIFT;
 	u64 length = bbio->bio.bi_iter.bi_size;
 	struct btrfs_io_stripe smap = { 0 };
 	int ret;
 
-	ASSERT(fs_info);
 	ASSERT(mirror_num > 0);
 	ASSERT(btrfs_op(&bbio->bio) == BTRFS_MAP_WRITE);
-	ASSERT(!bbio->inode);
+	ASSERT(!is_data_inode(bbio->inode));
+	ASSERT(bbio->is_scrub);
 
 	btrfs_bio_counter_inc_blocked(fs_info);
 	ret = btrfs_map_repair_block(fs_info, &smap, logical, length, mirror_num);

fs/btrfs/bio.h

@@ -27,7 +27,10 @@ typedef void (*btrfs_bio_end_io_t)(struct btrfs_bio *bbio);
 struct btrfs_bio {
 	/*
 	 * Inode and offset into it that this I/O operates on.
-	 * Only set for data I/O.
+	 *
+	 * If the inode is a data one, csum verification and read-repair
+	 * will be done automatically.
+	 * If the inode is a metadata one, everything is handled by the caller.
 	 */
 	struct btrfs_inode *inode;
 	u64 file_offset;
@@ -69,14 +72,17 @@ struct btrfs_bio {
 	atomic_t pending_ios;
 	struct work_struct end_io_work;
 
-	/* File system that this I/O operates on. */
-	struct btrfs_fs_info *fs_info;
-
 	/* Save the first error status of split bio. */
 	blk_status_t status;
 
 	/* Use the commit root to look up csums (data read bio only). */
 	bool csum_search_commit_root;
+
+	/*
+	 * Since scrub will reuse btree inode, we need this flag to distinguish
+	 * scrub bios.
+	 */
+	bool is_scrub;
 	/*
 	 * This member must come last, bio_alloc_bioset will allocate enough
 	 * bytes for entire btrfs_bio but relies on bio being last.
@@ -92,10 +98,10 @@ static inline struct btrfs_bio *btrfs_bio(struct bio *bio)
 int __init btrfs_bioset_init(void);
 void __cold btrfs_bioset_exit(void);
 
-void btrfs_bio_init(struct btrfs_bio *bbio, struct btrfs_fs_info *fs_info,
+void btrfs_bio_init(struct btrfs_bio *bbio, struct btrfs_inode *inode, u64 file_offset,
 		    btrfs_bio_end_io_t end_io, void *private);
 struct btrfs_bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf,
-				  struct btrfs_fs_info *fs_info,
+				  struct btrfs_inode *inode, u64 file_offset,
 				  btrfs_bio_end_io_t end_io, void *private);
 void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status);
 

fs/btrfs/compression.c

@@ -67,9 +67,7 @@ static struct compressed_bio *alloc_compressed_bio(struct btrfs_inode *inode,
 
 	bbio = btrfs_bio(bio_alloc_bioset(NULL, BTRFS_MAX_COMPRESSED_PAGES, op,
 					  GFP_NOFS, &btrfs_compressed_bioset));
-	btrfs_bio_init(bbio, inode->root->fs_info, end_io, NULL);
-	bbio->inode = inode;
-	bbio->file_offset = start;
+	btrfs_bio_init(bbio, inode, start, end_io, NULL);
 	return to_compressed_bio(bbio);
 }
 
@@ -354,7 +352,7 @@ static void end_bbio_compressed_write(struct btrfs_bio *bbio)
 
 static void btrfs_add_compressed_bio_folios(struct compressed_bio *cb)
 {
-	struct btrfs_fs_info *fs_info = cb->bbio.fs_info;
+	struct btrfs_fs_info *fs_info = cb->bbio.inode->root->fs_info;
 	struct bio *bio = &cb->bbio.bio;
 	u32 offset = 0;
 

fs/btrfs/compression.h

@@ -14,6 +14,7 @@
 #include <linux/pagemap.h>
 #include "bio.h"
 #include "fs.h"
+#include "btrfs_inode.h"
 
 struct address_space;
 struct inode;
@@ -74,7 +75,7 @@ struct compressed_bio {
 
 static inline struct btrfs_fs_info *cb_to_fs_info(const struct compressed_bio *cb)
 {
-	return cb->bbio.fs_info;
+	return cb->bbio.inode->root->fs_info;
 }
 
 /* @range_end must be exclusive. */

fs/btrfs/direct-io.c

@@ -715,10 +715,8 @@ static void btrfs_dio_submit_io(const struct iomap_iter *iter, struct bio *bio,
 		container_of(bbio, struct btrfs_dio_private, bbio);
 	struct btrfs_dio_data *dio_data = iter->private;
 
-	btrfs_bio_init(bbio, BTRFS_I(iter->inode)->root->fs_info,
+	btrfs_bio_init(bbio, BTRFS_I(iter->inode), file_offset,
 		       btrfs_dio_end_io, bio->bi_private);
-	bbio->inode = BTRFS_I(iter->inode);
-	bbio->file_offset = file_offset;
 
 	dip->file_offset = file_offset;
 	dip->bytes = bio->bi_iter.bi_size;

fs/btrfs/extent_io.c

@@ -517,7 +517,7 @@ static void end_folio_read(struct folio *folio, bool uptodate, u64 start, u32 le
  */
 static void end_bbio_data_write(struct btrfs_bio *bbio)
 {
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	struct bio *bio = &bbio->bio;
 	int error = blk_status_to_errno(bio->bi_status);
 	struct folio_iter fi;
@@ -573,7 +573,7 @@ static void begin_folio_read(struct btrfs_fs_info *fs_info, struct folio *folio)
  */
 static void end_bbio_data_read(struct btrfs_bio *bbio)
 {
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
 	struct bio *bio = &bbio->bio;
 	struct folio_iter fi;
 
@@ -738,12 +738,10 @@ static void alloc_new_bio(struct btrfs_inode *inode,
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_bio *bbio;
 
-	bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info,
-			       bio_ctrl->end_io_func, NULL);
+	bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, inode,
+			       file_offset, bio_ctrl->end_io_func, NULL);
 	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
 	bbio->bio.bi_write_hint = inode->vfs_inode.i_write_hint;
-	bbio->inode = inode;
-	bbio->file_offset = file_offset;
 	bio_ctrl->bbio = bbio;
 	bio_ctrl->len_to_oe_boundary = U32_MAX;
 	bio_ctrl->next_file_offset = file_offset;
@@ -2224,12 +2222,11 @@ static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
 
 	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
 			       REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),
-			       eb->fs_info, end_bbio_meta_write, eb);
+			       BTRFS_I(fs_info->btree_inode), eb->start,
+			       end_bbio_meta_write, eb);
 	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
 	bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
 	wbc_init_bio(wbc, &bbio->bio);
-	bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
-	bbio->file_offset = eb->start;
 	for (int i = 0; i < num_extent_folios(eb); i++) {
 		struct folio *folio = eb->folios[i];
 		u64 range_start = max_t(u64, eb->start, folio_pos(folio));
@@ -3844,6 +3841,7 @@ static void end_bbio_meta_read(struct btrfs_bio *bbio)
 int read_extent_buffer_pages_nowait(struct extent_buffer *eb, int mirror_num,
 				    const struct btrfs_tree_parent_check *check)
 {
+	struct btrfs_fs_info *fs_info = eb->fs_info;
 	struct btrfs_bio *bbio;
 
 	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
@@ -3877,11 +3875,9 @@ int read_extent_buffer_pages_nowait(struct extent_buffer *eb, int mirror_num,
 	refcount_inc(&eb->refs);
 
 	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
-			       REQ_OP_READ | REQ_META, eb->fs_info,
-			       end_bbio_meta_read, eb);
+			       REQ_OP_READ | REQ_META, BTRFS_I(fs_info->btree_inode),
+			       eb->start, end_bbio_meta_read, eb);
 	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
-	bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
-	bbio->file_offset = eb->start;
 	memcpy(&bbio->parent_check, check, sizeof(*check));
 	for (int i = 0; i < num_extent_folios(eb); i++) {
 		struct folio *folio = eb->folios[i];

fs/btrfs/inode.c

@@ -9402,7 +9402,6 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 					  u64 disk_bytenr, u64 disk_io_size,
 					  struct page **pages, void *uring_ctx)
 {
-	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_encoded_read_private *priv, sync_priv;
 	struct completion sync_reads;
 	unsigned long i = 0;
@@ -9427,10 +9426,9 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 	priv->status = 0;
 	priv->uring_ctx = uring_ctx;
 
-	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
+	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode, 0,
 			       btrfs_encoded_read_endio, priv);
 	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
-	bbio->inode = inode;
 
 	do {
 		size_t bytes = min_t(u64, disk_io_size, PAGE_SIZE);
@@ -9439,10 +9437,9 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 			refcount_inc(&priv->pending_refs);
 			btrfs_submit_bbio(bbio, 0);
 
-			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
+			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode, 0,
 					       btrfs_encoded_read_endio, priv);
 			bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
-			bbio->inode = inode;
 			continue;
 		}