[PATCH 1/4] erofs: add erofs_sb_free() helper

[PATCH 1/4] erofs: add erofs_sb_free() helper

[Gao Xiang]

Unify the common parts of erofs_fc_free() and erofs_kill_sb() as
erofs_sb_free().

Thus, fput() in erofs_fc_get_tree() is no longer needed, too.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/super.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index c235a8e4315e..1ce5ca11d32b 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -703,16 +703,19 @@ static int erofs_fc_get_tree(struct fs_context *fc)
 			GET_TREE_BDEV_QUIET_LOOKUP : 0);
 #ifdef CONFIG_EROFS_FS_BACKED_BY_FILE
 	if (ret == -ENOTBLK) {
+		struct file *file;
+
 		if (!fc->source)
 			return invalf(fc, "No source specified");
-		sbi->fdev = filp_open(fc->source, O_RDONLY | O_LARGEFILE, 0);
-		if (IS_ERR(sbi->fdev))
-			return PTR_ERR(sbi->fdev);
+
+		file = filp_open(fc->source, O_RDONLY | O_LARGEFILE, 0);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
+		sbi->fdev = file;
 
 		if (S_ISREG(file_inode(sbi->fdev)->i_mode) &&
 		    sbi->fdev->f_mapping->a_ops->read_folio)
 			return get_tree_nodev(fc, erofs_fc_fill_super);
-		fput(sbi->fdev);
 	}
 #endif
 	return ret;
@@ -763,19 +766,24 @@ static void erofs_free_dev_context(struct erofs_dev_context *devs)
 	kfree(devs);
 }
 
-static void erofs_fc_free(struct fs_context *fc)
+static void erofs_sb_free(struct erofs_sb_info *sbi)
 {
-	struct erofs_sb_info *sbi = fc->s_fs_info;
-
-	if (!sbi)
-		return;
-
 	erofs_free_dev_context(sbi->devs);
 	kfree(sbi->fsid);
 	kfree(sbi->domain_id);
+	if (sbi->fdev)
+		fput(sbi->fdev);
 	kfree(sbi);
 }
 
+static void erofs_fc_free(struct fs_context *fc)
+{
+	struct erofs_sb_info *sbi = fc->s_fs_info;
+
+	if (sbi) /* free here if an error occurs before transferring to sb */
+		erofs_sb_free(sbi);
+}
+
 static const struct fs_context_operations erofs_context_ops = {
 	.parse_param	= erofs_fc_parse_param,
 	.get_tree       = erofs_fc_get_tree,
@@ -813,15 +821,9 @@ static void erofs_kill_sb(struct super_block *sb)
 		kill_anon_super(sb);
 	else
 		kill_block_super(sb);
-
-	erofs_free_dev_context(sbi->devs);
 	fs_put_dax(sbi->dax_dev, NULL);
 	erofs_fscache_unregister_fs(sb);
-	kfree(sbi->fsid);
-	kfree(sbi->domain_id);
-	if (sbi->fdev)
-		fput(sbi->fdev);
-	kfree(sbi);
+	erofs_sb_free(sbi);
 	sb->s_fs_info = NULL;
 }
 
-- 
2.43.5

[PATCH 2/4] erofs: use `struct erofs_device_info` for the primary device

[Gao Xiang]

Instead of just listing each one directly in `struct erofs_sb_info`
except that we still use `sb->s_bdev` for the primary block device.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/data.c     | 10 +++-------
 fs/erofs/internal.h |  7 ++-----
 fs/erofs/super.c    | 27 +++++++++++++--------------
 3 files changed, 18 insertions(+), 26 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 1c49f8962021..0b0385fa3025 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -56,7 +56,7 @@ void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb)
 
 	buf->file = NULL;
 	if (erofs_is_fileio_mode(sbi)) {
-		buf->file = sbi->fdev;		/* some fs like FUSE needs it */
+		buf->file = sbi->dif0.file;	/* some fs like FUSE needs it */
 		buf->mapping = buf->file->f_mapping;
 	} else if (erofs_is_fscache_mode(sb))
 		buf->mapping = sbi->s_fscache->inode->i_mapping;
@@ -201,12 +201,8 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 	erofs_off_t startoff, length;
 	int id;
 
-	map->m_bdev = sb->s_bdev;
-	map->m_daxdev = EROFS_SB(sb)->dax_dev;
-	map->m_dax_part_off = EROFS_SB(sb)->dax_part_off;
-	map->m_fscache = EROFS_SB(sb)->s_fscache;
-	map->m_fp = EROFS_SB(sb)->fdev;
-
+	erofs_fill_from_devinfo(map, &EROFS_SB(sb)->dif0);
+	map->m_bdev = sb->s_bdev;	/* use s_bdev for the primary device */
 	if (map->m_deviceid) {
 		down_read(&devs->rwsem);
 		dif = idr_find(&devs->tree, map->m_deviceid - 1);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 1c847c30a918..6e91fcdeba94 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -107,6 +107,7 @@ struct erofs_xattr_prefix_item {
 };
 
 struct erofs_sb_info {
+	struct erofs_device_info dif0;
 	struct erofs_mount_opts opt;	/* options */
 #ifdef CONFIG_EROFS_FS_ZIP
 	/* list for all registered superblocks, mainly for shrinker */
@@ -124,13 +125,9 @@ struct erofs_sb_info {
 
 	struct erofs_sb_lz4_info lz4;
 #endif	/* CONFIG_EROFS_FS_ZIP */
-	struct file *fdev;
 	struct inode *packed_inode;
 	struct erofs_dev_context *devs;
-	struct dax_device *dax_dev;
-	u64 dax_part_off;
 	u64 total_blocks;
-	u32 primarydevice_blocks;
 
 	u32 meta_blkaddr;
 #ifdef CONFIG_EROFS_FS_XATTR
@@ -187,7 +184,7 @@ struct erofs_sb_info {
 
 static inline bool erofs_is_fileio_mode(struct erofs_sb_info *sbi)
 {
-	return IS_ENABLED(CONFIG_EROFS_FS_BACKED_BY_FILE) && sbi->fdev;
+	return IS_ENABLED(CONFIG_EROFS_FS_BACKED_BY_FILE) && sbi->dif0.file;
 }
 
 static inline bool erofs_is_fscache_mode(struct super_block *sb)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 1ce5ca11d32b..934fb1513095 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -203,7 +203,7 @@ static int erofs_scan_devices(struct super_block *sb,
 	struct erofs_device_info *dif;
 	int id, err = 0;
 
-	sbi->total_blocks = sbi->primarydevice_blocks;
+	sbi->total_blocks = sbi->dif0.blocks;
 	if (!erofs_sb_has_device_table(sbi))
 		ondisk_extradevs = 0;
 	else
@@ -307,7 +307,7 @@ static int erofs_read_superblock(struct super_block *sb)
 			  sbi->sb_size);
 		goto out;
 	}
-	sbi->primarydevice_blocks = le32_to_cpu(dsb->blocks);
+	sbi->dif0.blocks = le32_to_cpu(dsb->blocks);
 	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
 #ifdef CONFIG_EROFS_FS_XATTR
 	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
@@ -602,9 +602,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 			return -EINVAL;
 		}
 
-		sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev,
-						  &sbi->dax_part_off,
-						  NULL, NULL);
+		sbi->dif0.dax_dev = fs_dax_get_by_bdev(sb->s_bdev,
+				&sbi->dif0.dax_part_off, NULL, NULL);
 	}
 
 	err = erofs_read_superblock(sb);
@@ -627,7 +626,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 	}
 
 	if (test_opt(&sbi->opt, DAX_ALWAYS)) {
-		if (!sbi->dax_dev) {
+		if (!sbi->dif0.dax_dev) {
 			errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
 			clear_opt(&sbi->opt, DAX_ALWAYS);
 		} else if (sbi->blkszbits != PAGE_SHIFT) {
@@ -707,14 +706,13 @@ static int erofs_fc_get_tree(struct fs_context *fc)
 
 		if (!fc->source)
 			return invalf(fc, "No source specified");
-
 		file = filp_open(fc->source, O_RDONLY | O_LARGEFILE, 0);
 		if (IS_ERR(file))
 			return PTR_ERR(file);
-		sbi->fdev = file;
+		sbi->dif0.file = file;
 
-		if (S_ISREG(file_inode(sbi->fdev)->i_mode) &&
-		    sbi->fdev->f_mapping->a_ops->read_folio)
+		if (S_ISREG(file_inode(sbi->dif0.file)->i_mode) &&
+		    sbi->dif0.file->f_mapping->a_ops->read_folio)
 			return get_tree_nodev(fc, erofs_fc_fill_super);
 	}
 #endif
@@ -771,8 +769,8 @@ static void erofs_sb_free(struct erofs_sb_info *sbi)
 	erofs_free_dev_context(sbi->devs);
 	kfree(sbi->fsid);
 	kfree(sbi->domain_id);
-	if (sbi->fdev)
-		fput(sbi->fdev);
+	if (sbi->dif0.file)
+		fput(sbi->dif0.file);
 	kfree(sbi);
 }
 
@@ -817,11 +815,12 @@ static void erofs_kill_sb(struct super_block *sb)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 
-	if ((IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && sbi->fsid) || sbi->fdev)
+	if ((IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && sbi->fsid) ||
+	    sbi->dif0.file)
 		kill_anon_super(sb);
 	else
 		kill_block_super(sb);
-	fs_put_dax(sbi->dax_dev, NULL);
+	fs_put_dax(sbi->dif0.dax_dev, NULL);
 	erofs_fscache_unregister_fs(sb);
 	erofs_sb_free(sbi);
 	sb->s_fs_info = NULL;
-- 
2.43.5

[PATCH 3/4] erofs: reference `struct erofs_device_info` for erofs_map_dev

[Gao Xiang]

Record `m_sb` and `m_dif` to replace `m_fscache`, `m_daxdev`, `m_fp`
and `m_dax_part_off` in order to simplify the codebase.

Note that `m_bdev` is still left since it can be assigned from
`sb->s_bdev` directly.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/data.c     | 26 ++++++++++----------------
 fs/erofs/fileio.c   |  2 +-
 fs/erofs/internal.h |  6 ++----
 3 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 0b0385fa3025..63840971976c 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -179,19 +179,13 @@ int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map)
 }
 
 static void erofs_fill_from_devinfo(struct erofs_map_dev *map,
-				    struct erofs_device_info *dif)
+		struct super_block *sb, struct erofs_device_info *dif)
 {
+	map->m_sb = sb;
+	map->m_dif = dif;
 	map->m_bdev = NULL;
-	map->m_fp = NULL;
-	if (dif->file) {
-		if (S_ISBLK(file_inode(dif->file)->i_mode))
-			map->m_bdev = file_bdev(dif->file);
-		else
-			map->m_fp = dif->file;
-	}
-	map->m_daxdev = dif->dax_dev;
-	map->m_dax_part_off = dif->dax_part_off;
-	map->m_fscache = dif->fscache;
+	if (dif->file && S_ISBLK(file_inode(dif->file)->i_mode))
+		map->m_bdev = file_bdev(dif->file);
 }
 
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
@@ -201,7 +195,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 	erofs_off_t startoff, length;
 	int id;
 
-	erofs_fill_from_devinfo(map, &EROFS_SB(sb)->dif0);
+	erofs_fill_from_devinfo(map, sb, &EROFS_SB(sb)->dif0);
 	map->m_bdev = sb->s_bdev;	/* use s_bdev for the primary device */
 	if (map->m_deviceid) {
 		down_read(&devs->rwsem);
@@ -215,7 +209,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 			up_read(&devs->rwsem);
 			return 0;
 		}
-		erofs_fill_from_devinfo(map, dif);
+		erofs_fill_from_devinfo(map, sb, dif);
 		up_read(&devs->rwsem);
 	} else if (devs->extra_devices && !devs->flatdev) {
 		down_read(&devs->rwsem);
@@ -228,7 +222,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 			if (map->m_pa >= startoff &&
 			    map->m_pa < startoff + length) {
 				map->m_pa -= startoff;
-				erofs_fill_from_devinfo(map, dif);
+				erofs_fill_from_devinfo(map, sb, dif);
 				break;
 			}
 		}
@@ -298,7 +292,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 
 	iomap->offset = map.m_la;
 	if (flags & IOMAP_DAX)
-		iomap->dax_dev = mdev.m_daxdev;
+		iomap->dax_dev = mdev.m_dif->dax_dev;
 	else
 		iomap->bdev = mdev.m_bdev;
 	iomap->length = map.m_llen;
@@ -327,7 +321,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		iomap->type = IOMAP_MAPPED;
 		iomap->addr = mdev.m_pa;
 		if (flags & IOMAP_DAX)
-			iomap->addr += mdev.m_dax_part_off;
+			iomap->addr += mdev.m_dif->dax_part_off;
 	}
 	return 0;
 }
diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index 3af96b1e2c2a..a61b8faec651 100644
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -67,7 +67,7 @@ static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
 					     GFP_KERNEL | __GFP_NOFAIL);
 
 	bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
-	rq->iocb.ki_filp = mdev->m_fp;
+	rq->iocb.ki_filp = mdev->m_dif->file;
 	return rq;
 }
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 6e91fcdeba94..59e7739b7c3b 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -354,11 +354,9 @@ enum {
 };
 
 struct erofs_map_dev {
-	struct erofs_fscache *m_fscache;
+	struct super_block *m_sb;
+	struct erofs_device_info *m_dif;
 	struct block_device *m_bdev;
-	struct dax_device *m_daxdev;
-	struct file *m_fp;
-	u64 m_dax_part_off;
 
 	erofs_off_t m_pa;
 	unsigned int m_deviceid;
-- 
2.43.5

[PATCH 4/4] erofs: use buffered I/O for file-backed mounts by default

[Gao Xiang]

For many use cases (e.g. container images are just fetched from remote),
performance will be impacted if underlay page cache is up-to-date but
direct i/o will flush dirty pages first.

Instead, let's use buffered I/O by default and add a (re)mount option to
explicitly enable direct I/O if underlay files are supported too.

The startup time for containerd is improved as below:
                                     unpack        1st run  non-1st runs
EROFS snapshotter buffered I/O file  4.586404265s  0.308s   0.198s
EROFS snapshotter direct I/O file    4.581742849s  2.238s   0.222s
EROFS snapshotter loop               4.596023152s  0.346s   0.201s
Overlayfs snapshotter                5.382851037s  0.206s   0.214s

Fixes: fb176750266a ("erofs: add file-backed mount support")
Cc: Derek McGowan <derek@mcg.dev>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/fileio.c   |  7 +++++--
 fs/erofs/internal.h |  1 +
 fs/erofs/super.c    | 21 +++++++++++++--------
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index a61b8faec651..33f8539dda4a 100644
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -9,6 +9,7 @@ struct erofs_fileio_rq {
 	struct bio_vec bvecs[BIO_MAX_VECS];
 	struct bio bio;
 	struct kiocb iocb;
+	struct super_block *sb;
 };
 
 struct erofs_fileio {
@@ -52,8 +53,9 @@ static void erofs_fileio_rq_submit(struct erofs_fileio_rq *rq)
 	rq->iocb.ki_pos = rq->bio.bi_iter.bi_sector << SECTOR_SHIFT;
 	rq->iocb.ki_ioprio = get_current_ioprio();
 	rq->iocb.ki_complete = erofs_fileio_ki_complete;
-	rq->iocb.ki_flags = (rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT) ?
-				IOCB_DIRECT : 0;
+	if (test_opt(&EROFS_SB(rq->sb)->opt, DIRECT_IO) &&
+	    rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT)
+		rq->iocb.ki_flags = IOCB_DIRECT;
 	iov_iter_bvec(&iter, ITER_DEST, rq->bvecs, rq->bio.bi_vcnt,
 		      rq->bio.bi_iter.bi_size);
 	ret = vfs_iocb_iter_read(rq->iocb.ki_filp, &rq->iocb, &iter);
@@ -68,6 +70,7 @@ static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
 
 	bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
 	rq->iocb.ki_filp = mdev->m_dif->file;
+	rq->sb = mdev->m_sb;
 	return rq;
 }
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 59e7739b7c3b..bc46000ccc6b 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -177,6 +177,7 @@ struct erofs_sb_info {
 #define EROFS_MOUNT_POSIX_ACL		0x00000020
 #define EROFS_MOUNT_DAX_ALWAYS		0x00000040
 #define EROFS_MOUNT_DAX_NEVER		0x00000080
+#define EROFS_MOUNT_DIRECT_IO		0x00000100
 
 #define clear_opt(opt, option)	((opt)->mount_opt &= ~EROFS_MOUNT_##option)
 #define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 934fb1513095..cbb9566cc6dc 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -364,14 +364,8 @@ static void erofs_default_options(struct erofs_sb_info *sbi)
 }
 
 enum {
-	Opt_user_xattr,
-	Opt_acl,
-	Opt_cache_strategy,
-	Opt_dax,
-	Opt_dax_enum,
-	Opt_device,
-	Opt_fsid,
-	Opt_domain_id,
+	Opt_user_xattr, Opt_acl, Opt_cache_strategy, Opt_dax, Opt_dax_enum,
+	Opt_device, Opt_fsid, Opt_domain_id, Opt_directio,
 	Opt_err
 };
 
@@ -398,6 +392,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
 	fsparam_string("device",	Opt_device),
 	fsparam_string("fsid",		Opt_fsid),
 	fsparam_string("domain_id",	Opt_domain_id),
+	fsparam_flag_no("directio",	Opt_directio),
 	{}
 };
 
@@ -511,6 +506,16 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 		errorfc(fc, "%s option not supported", erofs_fs_parameters[opt].name);
 		break;
 #endif
+	case Opt_directio:
+#ifdef CONFIG_EROFS_FS_BACKED_BY_FILE
+		if (result.boolean)
+			set_opt(&sbi->opt, DIRECT_IO);
+		else
+			clear_opt(&sbi->opt, DIRECT_IO);
+#else
+		errorfc(fc, "%s option not supported", erofs_fs_parameters[opt].name);
+#endif
+		break;
 	default:
 		return -ENOPARAM;
 	}
-- 
2.43.5

[PATCH v2 4/4] erofs: use buffered I/O for file-backed mounts by default

[Gao Xiang]

For many use cases (e.g. container images are just fetched from remote),
performance will be impacted if underlay page cache is up-to-date but
direct i/o flushes dirty pages first.

Instead, let's use buffered I/O by default to keep in sync with loop
devices and add a (re)mount option to explicitly enable direct I/O
if supported by the underlying files.

The container startup time is improved as below:
                                     unpack        1st run  non-1st runs
EROFS snapshotter buffered I/O file  4.586404265s  0.308s   0.198s
EROFS snapshotter direct I/O file    4.581742849s  2.238s   0.222s
EROFS snapshotter loop               4.596023152s  0.346s   0.201s
Overlayfs snapshotter                5.382851037s  0.206s   0.214s

Fixes: fb176750266a ("erofs: add file-backed mount support")
Cc: Derek McGowan <derek@mcg.dev>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
v1: https://lore.kernel.org/r/20241212133504.2047178-4-hsiangkao@linux.alibaba.com
changes since v1 (obsoleted version by mistake):
 - refine commit message;
 - add `directio` in erofs_show_options() too.

 fs/erofs/fileio.c   |  7 +++++--
 fs/erofs/internal.h |  1 +
 fs/erofs/super.c    | 23 +++++++++++++++--------
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index a61b8faec651..33f8539dda4a 100644
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -9,6 +9,7 @@ struct erofs_fileio_rq {
 	struct bio_vec bvecs[BIO_MAX_VECS];
 	struct bio bio;
 	struct kiocb iocb;
+	struct super_block *sb;
 };
 
 struct erofs_fileio {
@@ -52,8 +53,9 @@ static void erofs_fileio_rq_submit(struct erofs_fileio_rq *rq)
 	rq->iocb.ki_pos = rq->bio.bi_iter.bi_sector << SECTOR_SHIFT;
 	rq->iocb.ki_ioprio = get_current_ioprio();
 	rq->iocb.ki_complete = erofs_fileio_ki_complete;
-	rq->iocb.ki_flags = (rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT) ?
-				IOCB_DIRECT : 0;
+	if (test_opt(&EROFS_SB(rq->sb)->opt, DIRECT_IO) &&
+	    rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT)
+		rq->iocb.ki_flags = IOCB_DIRECT;
 	iov_iter_bvec(&iter, ITER_DEST, rq->bvecs, rq->bio.bi_vcnt,
 		      rq->bio.bi_iter.bi_size);
 	ret = vfs_iocb_iter_read(rq->iocb.ki_filp, &rq->iocb, &iter);
@@ -68,6 +70,7 @@ static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
 
 	bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
 	rq->iocb.ki_filp = mdev->m_dif->file;
+	rq->sb = mdev->m_sb;
 	return rq;
 }
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 59e7739b7c3b..bc46000ccc6b 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -177,6 +177,7 @@ struct erofs_sb_info {
 #define EROFS_MOUNT_POSIX_ACL		0x00000020
 #define EROFS_MOUNT_DAX_ALWAYS		0x00000040
 #define EROFS_MOUNT_DAX_NEVER		0x00000080
+#define EROFS_MOUNT_DIRECT_IO		0x00000100
 
 #define clear_opt(opt, option)	((opt)->mount_opt &= ~EROFS_MOUNT_##option)
 #define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 9044907354e1..f5956474bfde 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -364,14 +364,8 @@ static void erofs_default_options(struct erofs_sb_info *sbi)
 }
 
 enum {
-	Opt_user_xattr,
-	Opt_acl,
-	Opt_cache_strategy,
-	Opt_dax,
-	Opt_dax_enum,
-	Opt_device,
-	Opt_fsid,
-	Opt_domain_id,
+	Opt_user_xattr, Opt_acl, Opt_cache_strategy, Opt_dax, Opt_dax_enum,
+	Opt_device, Opt_fsid, Opt_domain_id, Opt_directio,
 	Opt_err
 };
 
@@ -398,6 +392,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
 	fsparam_string("device",	Opt_device),
 	fsparam_string("fsid",		Opt_fsid),
 	fsparam_string("domain_id",	Opt_domain_id),
+	fsparam_flag_no("directio",	Opt_directio),
 	{}
 };
 
@@ -511,6 +506,16 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 		errorfc(fc, "%s option not supported", erofs_fs_parameters[opt].name);
 		break;
 #endif
+	case Opt_directio:
+#ifdef CONFIG_EROFS_FS_BACKED_BY_FILE
+		if (result.boolean)
+			set_opt(&sbi->opt, DIRECT_IO);
+		else
+			clear_opt(&sbi->opt, DIRECT_IO);
+#else
+		errorfc(fc, "%s option not supported", erofs_fs_parameters[opt].name);
+#endif
+		break;
 	default:
 		return -ENOPARAM;
 	}
@@ -948,6 +953,8 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_puts(seq, ",dax=always");
 	if (test_opt(opt, DAX_NEVER))
 		seq_puts(seq, ",dax=never");
+	if (erofs_is_fileio_mode(sbi) && test_opt(opt, DIRECT_IO))
+		seq_puts(seq, ",directio");
 #ifdef CONFIG_EROFS_FS_ONDEMAND
 	if (sbi->fsid)
 		seq_printf(seq, ",fsid=%s", sbi->fsid);
-- 
2.43.5

Re: [PATCH 1/4] erofs: add erofs_sb_free() helper

[Chao Yu]

On 2024/12/12 21:35, Gao Xiang wrote:
> Unify the common parts of erofs_fc_free() and erofs_kill_sb() as
> erofs_sb_free().
> 
> Thus, fput() in erofs_fc_get_tree() is no longer needed, too.
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [PATCH 2/4] erofs: use `struct erofs_device_info` for the primary device

[Chao Yu]

On 2024/12/12 21:35, Gao Xiang wrote:
> Instead of just listing each one directly in `struct erofs_sb_info`
> except that we still use `sb->s_bdev` for the primary block device.
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [PATCH 3/4] erofs: reference `struct erofs_device_info` for erofs_map_dev

[Chao Yu]

On 2024/12/12 21:35, Gao Xiang wrote:
> Record `m_sb` and `m_dif` to replace `m_fscache`, `m_daxdev`, `m_fp`
> and `m_dax_part_off` in order to simplify the codebase.
> 
> Note that `m_bdev` is still left since it can be assigned from
> `sb->s_bdev` directly.
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [PATCH v2 4/4] erofs: use buffered I/O for file-backed mounts by default

[Chao Yu]

On 2024/12/12 21:43, Gao Xiang wrote:
> For many use cases (e.g. container images are just fetched from remote),
> performance will be impacted if underlay page cache is up-to-date but
> direct i/o flushes dirty pages first.
> 
> Instead, let's use buffered I/O by default to keep in sync with loop
> devices and add a (re)mount option to explicitly enable direct I/O
> if supported by the underlying files.
> 
> The container startup time is improved as below:
>                                       unpack        1st run  non-1st runs
> EROFS snapshotter buffered I/O file  4.586404265s  0.308s   0.198s
> EROFS snapshotter direct I/O file    4.581742849s  2.238s   0.222s
> EROFS snapshotter loop               4.596023152s  0.346s   0.201s
> Overlayfs snapshotter                5.382851037s  0.206s   0.214s
> 
> Fixes: fb176750266a ("erofs: add file-backed mount support")
> Cc: Derek McGowan <derek@mcg.dev>
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

[PATCH v2 3/4] erofs: reference `struct erofs_device_info` for erofs_map_dev

[Gao Xiang]

Record `m_sb` and `m_dif` to replace `m_fscache`, `m_daxdev`, `m_fp`
and `m_dax_part_off` in order to simplify the codebase.

Note that `m_bdev` is still left since it can be assigned from
`sb->s_bdev` directly.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
v1: https://lore.kernel.org/r/20241212133504.2047178-3-hsiangkao@linux.alibaba.com
changes since v1:
 - fix fscache build.

 fs/erofs/data.c     | 26 ++++++++++----------------
 fs/erofs/fileio.c   |  2 +-
 fs/erofs/fscache.c  |  4 ++--
 fs/erofs/internal.h |  6 ++----
 4 files changed, 15 insertions(+), 23 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 0b0385fa3025..63840971976c 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -179,19 +179,13 @@ int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map)
 }
 
 static void erofs_fill_from_devinfo(struct erofs_map_dev *map,
-				    struct erofs_device_info *dif)
+		struct super_block *sb, struct erofs_device_info *dif)
 {
+	map->m_sb = sb;
+	map->m_dif = dif;
 	map->m_bdev = NULL;
-	map->m_fp = NULL;
-	if (dif->file) {
-		if (S_ISBLK(file_inode(dif->file)->i_mode))
-			map->m_bdev = file_bdev(dif->file);
-		else
-			map->m_fp = dif->file;
-	}
-	map->m_daxdev = dif->dax_dev;
-	map->m_dax_part_off = dif->dax_part_off;
-	map->m_fscache = dif->fscache;
+	if (dif->file && S_ISBLK(file_inode(dif->file)->i_mode))
+		map->m_bdev = file_bdev(dif->file);
 }
 
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
@@ -201,7 +195,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 	erofs_off_t startoff, length;
 	int id;
 
-	erofs_fill_from_devinfo(map, &EROFS_SB(sb)->dif0);
+	erofs_fill_from_devinfo(map, sb, &EROFS_SB(sb)->dif0);
 	map->m_bdev = sb->s_bdev;	/* use s_bdev for the primary device */
 	if (map->m_deviceid) {
 		down_read(&devs->rwsem);
@@ -215,7 +209,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 			up_read(&devs->rwsem);
 			return 0;
 		}
-		erofs_fill_from_devinfo(map, dif);
+		erofs_fill_from_devinfo(map, sb, dif);
 		up_read(&devs->rwsem);
 	} else if (devs->extra_devices && !devs->flatdev) {
 		down_read(&devs->rwsem);
@@ -228,7 +222,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 			if (map->m_pa >= startoff &&
 			    map->m_pa < startoff + length) {
 				map->m_pa -= startoff;
-				erofs_fill_from_devinfo(map, dif);
+				erofs_fill_from_devinfo(map, sb, dif);
 				break;
 			}
 		}
@@ -298,7 +292,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 
 	iomap->offset = map.m_la;
 	if (flags & IOMAP_DAX)
-		iomap->dax_dev = mdev.m_daxdev;
+		iomap->dax_dev = mdev.m_dif->dax_dev;
 	else
 		iomap->bdev = mdev.m_bdev;
 	iomap->length = map.m_llen;
@@ -327,7 +321,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		iomap->type = IOMAP_MAPPED;
 		iomap->addr = mdev.m_pa;
 		if (flags & IOMAP_DAX)
-			iomap->addr += mdev.m_dax_part_off;
+			iomap->addr += mdev.m_dif->dax_part_off;
 	}
 	return 0;
 }
diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index 3af96b1e2c2a..a61b8faec651 100644
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -67,7 +67,7 @@ static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
 					     GFP_KERNEL | __GFP_NOFAIL);
 
 	bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
-	rq->iocb.ki_filp = mdev->m_fp;
+	rq->iocb.ki_filp = mdev->m_dif->file;
 	return rq;
 }
 
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index fda16eedafb5..1268baa2ecc4 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -198,7 +198,7 @@ struct bio *erofs_fscache_bio_alloc(struct erofs_map_dev *mdev)
 
 	io = kmalloc(sizeof(*io), GFP_KERNEL | __GFP_NOFAIL);
 	bio_init(&io->bio, NULL, io->bvecs, BIO_MAX_VECS, REQ_OP_READ);
-	io->io.private = mdev->m_fscache->cookie;
+	io->io.private = mdev->m_dif->fscache->cookie;
 	io->io.end_io = erofs_fscache_bio_endio;
 	refcount_set(&io->io.ref, 1);
 	return &io->bio;
@@ -316,7 +316,7 @@ static int erofs_fscache_data_read_slice(struct erofs_fscache_rq *req)
 	if (!io)
 		return -ENOMEM;
 	iov_iter_xarray(&io->iter, ITER_DEST, &mapping->i_pages, pos, count);
-	ret = erofs_fscache_read_io_async(mdev.m_fscache->cookie,
+	ret = erofs_fscache_read_io_async(mdev.m_dif->fscache->cookie,
 			mdev.m_pa + (pos - map.m_la), io);
 	erofs_fscache_req_io_put(io);
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 6e91fcdeba94..59e7739b7c3b 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -354,11 +354,9 @@ enum {
 };
 
 struct erofs_map_dev {
-	struct erofs_fscache *m_fscache;
+	struct super_block *m_sb;
+	struct erofs_device_info *m_dif;
 	struct block_device *m_bdev;
-	struct dax_device *m_daxdev;
-	struct file *m_fp;
-	u64 m_dax_part_off;
 
 	erofs_off_t m_pa;
 	unsigned int m_deviceid;
-- 
2.43.5