[PATCH] erofs: introduce nolargefolio mount option

[Chao Yu]

This patch introduces a new mount option 'nolargefolio' for EROFS.
When this option is specified, large folio will be disabled by
default for all inodes, this option can be used for environments
where large folio resources are limited, it's necessary to only
let specified user to allocate large folios on demand.

Signed-off-by: Chao Yu <chao at kernel.org>
---
 Documentation/filesystems/erofs.rst | 1 +
 fs/erofs/inode.c                    | 3 ++-
 fs/erofs/internal.h                 | 1 +
 fs/erofs/super.c                    | 8 +++++++-
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/filesystems/erofs.rst b/Documentation/filesystems/erofs.rst
index fe06308e546c..d692a1d9f32c 100644
--- a/Documentation/filesystems/erofs.rst
+++ b/Documentation/filesystems/erofs.rst
@@ -137,6 +137,7 @@ fsoffset=%llu          Specify block-aligned filesystem offset for the primary d
 inode_share            Enable inode page sharing for this filesystem.  Inodes with
                        identical content within the same domain ID can share the
                        page cache.
+nolargefolio           Disable large folio support for all files.
 ===================    =========================================================
 
 Sysfs Entries
diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 4b3d21402e10..26361e86a354 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -254,7 +254,8 @@ static int erofs_fill_inode(struct inode *inode)
 		return 0;
 	}
 
-	mapping_set_large_folios(inode->i_mapping);
+	if (!test_opt(&EROFS_SB(inode->i_sb)->opt, NO_LARGE_FOLIO))
+		mapping_set_large_folios(inode->i_mapping);
 	aops = erofs_get_aops(inode, false);
 	if (IS_ERR(aops))
 		return PTR_ERR(aops);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index a4f0a42cf8c3..b5d98410c699 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -177,6 +177,7 @@ struct erofs_sb_info {
 #define EROFS_MOUNT_DAX_NEVER		0x00000080
 #define EROFS_MOUNT_DIRECT_IO		0x00000100
 #define EROFS_MOUNT_INODE_SHARE		0x00000200
+#define EROFS_MOUNT_NO_LARGE_FOLIO	0x00000400
 
 #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 972a0c82198d..a353369d4db8 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -390,7 +390,7 @@ 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_directio, Opt_fsoffset,
-	Opt_inode_share,
+	Opt_inode_share, Opt_nolargefolio,
 };
 
 static const struct constant_table erofs_param_cache_strategy[] = {
@@ -419,6 +419,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
 	fsparam_flag_no("directio",	Opt_directio),
 	fsparam_u64("fsoffset",		Opt_fsoffset),
 	fsparam_flag("inode_share",	Opt_inode_share),
+	fsparam_flag("nolargefolio",	Opt_nolargefolio),
 	{}
 };
 
@@ -541,6 +542,9 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 		else
 			set_opt(&sbi->opt, INODE_SHARE);
 		break;
+	case Opt_nolargefolio:
+		set_opt(&sbi->opt, NO_LARGE_FOLIO);
+		break;
 	}
 	return 0;
 }
@@ -1105,6 +1109,8 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_printf(seq, ",fsoffset=%llu", sbi->dif0.fsoff);
 	if (test_opt(opt, INODE_SHARE))
 		seq_puts(seq, ",inode_share");
+	if (test_opt(opt, NO_LARGE_FOLIO))
+		seq_puts(seq, ",nolargefolio");
 	return 0;
 }
 
-- 
2.49.0