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Message-ID: <20230306153108.00006877.zbestahu@gmail.com>
Date: Mon, 6 Mar 2023 15:31:08 +0800
From: Yue Hu <zbestahu@...il.com>
To: Jingbo Xu <jefflexu@...ux.alibaba.com>
Cc: xiang@...nel.org, chao@...nel.org, linux-erofs@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, huyue2@...lpad.com,
zhangwen@...lpad.com
Subject: Re: [PATCH v4 2/2] erofs: set block size to the on-disk block size
On Thu, 2 Mar 2023 22:39:15 +0800
Jingbo Xu <jefflexu@...ux.alibaba.com> wrote:
> Set the block size to that specified in on-disk superblock.
>
> Also remove the hard constraint of PAGE_SIZE block size for the
> uncompressed device backend. This constraint is temporarily remained
> for compressed device and fscache backend, as there is more work needed
> to handle the condition where the block size is not equal to PAGE_SIZE.
>
> It is worth noting that the on-disk block size is read prior to
> erofs_superblock_csum_verify(), as the read block size is needed in the
> latter.
>
> Besides, later we are going to make erofs refer to tar data blobs (which
> is 512-byte aligned) for OCI containers, where the block size is 512
> bytes. In this case, the 512-byte block size may not be adequate for a
> directory to contain enough dirents. To fix this, we are also going to
> introduce directory block size independent on the block size.
>
> Due to we have already supported block size smaller than PAGE_SIZE now,
> disable all these images with such separated directory block size until
> we supported this feature later.
>
> Signed-off-by: Jingbo Xu <jefflexu@...ux.alibaba.com>
> ---
> fs/erofs/erofs_fs.h | 5 +++--
> fs/erofs/inode.c | 3 ++-
> fs/erofs/internal.h | 11 ++---------
> fs/erofs/super.c | 46 +++++++++++++++++++++++++++++----------------
> 4 files changed, 37 insertions(+), 28 deletions(-)
>
> diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
> index dbcd24371002..ac9c2ff3aa66 100644
> --- a/fs/erofs/erofs_fs.h
> +++ b/fs/erofs/erofs_fs.h
> @@ -53,7 +53,7 @@ struct erofs_super_block {
> __le32 magic; /* file system magic number */
> __le32 checksum; /* crc32c(super_block) */
> __le32 feature_compat;
> - __u8 blkszbits; /* support block_size == PAGE_SIZE only */
> + __u8 blkszbits; /* filesystem block size */
/* filesystem block size in bit shift */
> __u8 sb_extslots; /* superblock size = 128 + sb_extslots * 16 */
>
> __le16 root_nid; /* nid of root directory */
> @@ -75,7 +75,8 @@ struct erofs_super_block {
> } __packed u1;
> __le16 extra_devices; /* # of devices besides the primary device */
> __le16 devt_slotoff; /* startoff = devt_slotoff * devt_slotsize */
> - __u8 reserved[6];
> + __u8 dirblkbits; /* directory block size */
Ditto.
> + __u8 reserved[5];
> __le64 packed_nid; /* nid of the special packed inode */
> __u8 reserved2[24];
> };
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index de26dac4e07e..0e6ff8a98c68 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -291,7 +291,8 @@ static int erofs_fill_inode(struct inode *inode)
> }
>
> if (erofs_inode_is_data_compressed(vi->datalayout)) {
> - if (!erofs_is_fscache_mode(inode->i_sb))
> + if (!erofs_is_fscache_mode(inode->i_sb) &&
> + inode->i_sb->s_blocksize_bits == PAGE_SHIFT)
> err = z_erofs_fill_inode(inode);
> else
> err = -EOPNOTSUPP;
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index d8019d835405..f99ba4061a3b 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -148,7 +148,8 @@ struct erofs_sb_info {
> u16 device_id_mask; /* valid bits of device id to be used */
>
> unsigned char islotbits; /* inode slot unit size in bit shift */
> - unsigned char blkszbits;
> + unsigned char blkszbits; /* filesystem block size */
Ditto.
> + unsigned char dirblkbits; /* directory block size */
Ditto.
>
> u32 sb_size; /* total superblock size */
> u32 build_time_nsec;
> @@ -240,14 +241,6 @@ static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
> VAL != EROFS_LOCKED_MAGIC);
> }
>
> -/* we strictly follow PAGE_SIZE and no buffer head yet */
> -#define LOG_BLOCK_SIZE PAGE_SHIFT
> -#define EROFS_BLKSIZ (1 << LOG_BLOCK_SIZE)
> -
> -#if (EROFS_BLKSIZ % 4096 || !EROFS_BLKSIZ)
> -#error erofs cannot be used in this platform
> -#endif
> -
> enum erofs_kmap_type {
> EROFS_NO_KMAP, /* don't map the buffer */
> EROFS_KMAP, /* use kmap_local_page() to map the buffer */
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index c97615c96ef8..d5fa0f582cbe 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -330,7 +330,6 @@ static int erofs_read_superblock(struct super_block *sb)
> struct erofs_sb_info *sbi;
> struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
> struct erofs_super_block *dsb;
> - unsigned int blkszbits;
> void *data;
> int ret;
>
> @@ -349,6 +348,17 @@ static int erofs_read_superblock(struct super_block *sb)
> goto out;
> }
>
> + sbi->blkszbits = dsb->blkszbits;
> + sbi->dirblkbits = dsb->dirblkbits;
> + if (sbi->blkszbits < 9 || sbi->blkszbits > PAGE_SHIFT) {
> + erofs_err(sb, "blkszbits %u isn't supported", sbi->blkszbits);
> + goto out;
> + }
> + if (sbi->dirblkbits) {
> + erofs_err(sb, "dirblkbits %u isn't supported", sbi->dirblkbits);
> + goto out;
> + }
> +
> sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
> if (erofs_sb_has_sb_chksum(sbi)) {
> ret = erofs_superblock_csum_verify(sb, data);
> @@ -357,19 +367,11 @@ static int erofs_read_superblock(struct super_block *sb)
> }
>
> ret = -EINVAL;
> - blkszbits = dsb->blkszbits;
> - /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
> - if (blkszbits != LOG_BLOCK_SIZE) {
> - erofs_err(sb, "blkszbits %u isn't supported on this platform",
> - blkszbits);
> - goto out;
> - }
> -
> if (!check_layout_compatibility(sb, dsb))
> goto out;
>
> sbi->sb_size = 128 + dsb->sb_extslots * EROFS_SB_EXTSLOT_SIZE;
> - if (sbi->sb_size > EROFS_BLKSIZ) {
> + if (sbi->sb_size > PAGE_SIZE - EROFS_SUPER_OFFSET) {
> erofs_err(sb, "invalid sb_extslots %u (more than a fs block)",
> sbi->sb_size);
> goto out;
> @@ -736,8 +738,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>
> sbi->blkszbits = PAGE_SHIFT;
> if (erofs_is_fscache_mode(sb)) {
> - sb->s_blocksize = EROFS_BLKSIZ;
> - sb->s_blocksize_bits = LOG_BLOCK_SIZE;
> + sb->s_blocksize = PAGE_SIZE;
> + sb->s_blocksize_bits = PAGE_SHIFT;
>
> err = erofs_fscache_register_fs(sb);
> if (err)
> @@ -747,8 +749,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
> if (err)
> return err;
> } else {
> - if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
> - erofs_err(sb, "failed to set erofs blksize");
> + if (!sb_set_blocksize(sb, PAGE_SIZE)) {
> + errorfc(fc, "failed to set initial blksize");
> return -EINVAL;
> }
>
> @@ -761,12 +763,24 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
> if (err)
> return err;
>
> - if (test_opt(&sbi->opt, DAX_ALWAYS)) {
> - BUILD_BUG_ON(EROFS_BLKSIZ != PAGE_SIZE);
> + if (sb->s_blocksize_bits != sbi->blkszbits) {
> + if (erofs_is_fscache_mode(sb)) {
> + errorfc(fc, "unsupported blksize for fscache mode");
> + return -EINVAL;
> + }
> + if (!sb_set_blocksize(sb, 1 << sbi->blkszbits)) {
> + errorfc(fc, "failed to set erofs blksize");
> + return -EINVAL;
> + }
> + }
>
> + if (test_opt(&sbi->opt, DAX_ALWAYS)) {
> if (!sbi->dax_dev) {
> errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
> clear_opt(&sbi->opt, DAX_ALWAYS);
> + } else if (sbi->blkszbits != PAGE_SHIFT) {
> + errorfc(fc, "unsupported blocksize for DAX");
> + clear_opt(&sbi->opt, DAX_ALWAYS);
> }
> }
>
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