Hi Greg,

Sorry for annoying... Could you help merge these two fixes? Thanks in advance... decompression inplace optimization needs these two patches and I will integrate erofs decompression inplace optimization later for linux-next 5.3, and try to start making effort on moving to fs/ directory on kernel 5.4...

Thanks, Gao Xiang

On 2019/6/13 16:35, Gao Xiang wrote:

There are some backward incompatible features pending for months, mainly due to on-disk format expensions.

However, we should ensure that it cannot be mounted with old kernels. Otherwise, it will causes unexpected behaviors.

Fixes: ba2b77a82022 ("staging: erofs: add super block operations") Cc: stable@vger.kernel.org # 4.19+ Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com

---

change log v3:

• record requirements in erofs_sb_info for runtime use as well;

change log v2:

• update printed message

drivers/staging/erofs/erofs_fs.h | 13 ++++++++++--- drivers/staging/erofs/internal.h | 2 ++ drivers/staging/erofs/super.c | 19 +++++++++++++++++++ 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h index fa52898df006..8ddb2b3e7d39 100644 --- a/drivers/staging/erofs/erofs_fs.h +++ b/drivers/staging/erofs/erofs_fs.h @@ -17,10 +17,16 @@ #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2 #define EROFS_SUPER_OFFSET 1024 +/*

• • Any bits that aren't in EROFS_ALL_REQUIREMENTS should be
• • incompatible with this kernel version.
• */

+#define EROFS_ALL_REQUIREMENTS 0

struct erofs_super_block { /* 0 */__le32 magic; /* in the little endian */ /* 4 */__le32 checksum; /* crc32c(super_block) */ -/* 8 */__le32 features; +/* 8 */__le32 features; /* (aka. feature_compat) */ /* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */ /* 13 */__u8 reserved; @@ -34,9 +40,10 @@ struct erofs_super_block { /* 44 */__le32 xattr_blkaddr; /* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */ /* 64 */__u8 volume_name[16]; /* volume name */ +/* 80 */__le32 requirements; /* (aka. feature_incompat) */ -/* 80 */__u8 reserved2[48]; /* 128 bytes */ -} __packed; +/* 84 */__u8 reserved2[44]; +} __packed; /* 128 bytes */ /*

• erofs inode data mapping:

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h index 911333cdeef4..fc732c86ecd8 100644 --- a/drivers/staging/erofs/internal.h +++ b/drivers/staging/erofs/internal.h @@ -115,6 +115,8 @@ struct erofs_sb_info { u8 uuid[16]; /* 128-bit uuid for volume */ u8 volume_name[16]; /* volume name */

• u32 requirements;
• char *dev_name;

unsigned int mount_opt; diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c index f580d4ef77a1..cadbcc11702a 100644 --- a/drivers/staging/erofs/super.c +++ b/drivers/staging/erofs/super.c @@ -71,6 +71,22 @@ static void free_inode(struct inode *inode) kmem_cache_free(erofs_inode_cachep, vi); } +static bool check_layout_compatibility(struct super_block *sb,

• 		       struct erofs_super_block *layout)
  

+{

• const unsigned int requirements = le32_to_cpu(layout->requirements);
• EROFS_SB(sb)->requirements = requirements;
• /* check if current kernel meets all mandatory requirements */
• if (requirements & (~EROFS_ALL_REQUIREMENTS)) {

• errln("unidentified requirements %x, please upgrade kernel version",
  

•       requirements & ~EROFS_ALL_REQUIREMENTS);
  

• return false;
  

• }
• return true;

+}

static int superblock_read(struct super_block *sb) { struct erofs_sb_info *sbi; @@ -104,6 +120,9 @@ static int superblock_read(struct super_block *sb) goto out; }

• if (!check_layout_compatibility(sb, layout))

• goto out;
  

• sbi->blocks = le32_to_cpu(layout->blocks); sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr);

#ifdef CONFIG_EROFS_FS_XATTR