Hi Pratik, Some comments as below...
On Mon, Oct 21, 2019 at 12:58:28AM +0530, Pratik Shinde wrote: > Patch for kernel side changes of checksum feature.I used kernel's > crc32c library for calculating the checksum. > > Signed-off-by: Pratik Shinde <[email protected]> > --- > fs/erofs/erofs_fs.h | 5 +++-- > fs/erofs/internal.h | 2 +- > fs/erofs/super.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++---- > 3 files changed, 50 insertions(+), 7 deletions(-) > > diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h > index b1ee565..bab5506 100644 > --- a/fs/erofs/erofs_fs.h > +++ b/fs/erofs/erofs_fs.h > @@ -17,6 +17,7 @@ > */ > #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001 > #define EROFS_ALL_FEATURE_INCOMPAT > EROFS_FEATURE_INCOMPAT_LZ4_0PADDING > +#define EROFS_FEATURE_SB_CHKSUM 0x0001 How about keeping in sync with erofs-utils? > > /* 128-byte erofs on-disk super block */ > struct erofs_super_block { > @@ -37,8 +38,8 @@ struct erofs_super_block { > __u8 uuid[16]; /* 128-bit uuid for volume */ > __u8 volume_name[16]; /* volume name */ > __le32 feature_incompat; > - > - __u8 reserved2[44]; > + __le32 chksum_blocks; /* number of blocks used for checksum */ > + __u8 reserved2[40]; > }; > > /* > diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h > index 544a453..cd3af45 100644 > --- a/fs/erofs/internal.h > +++ b/fs/erofs/internal.h > @@ -86,7 +86,7 @@ struct erofs_sb_info { > u8 uuid[16]; /* 128-bit uuid for volume */ > u8 volume_name[16]; /* volume name */ > u32 feature_incompat; > - > + u32 features; no use? and how about keeping in sync with erofs-utils, naming feature_compat as well? see, https://lore.kernel.org/r/20191020141102.GA30399@hsiangkao-HP-ZHAN-66-Pro-G1/ > unsigned int mount_opt; > }; > > diff --git a/fs/erofs/super.c b/fs/erofs/super.c > index 0e36949..94e1d6a 100644 > --- a/fs/erofs/super.c > +++ b/fs/erofs/super.c > @@ -9,6 +9,7 @@ > #include <linux/statfs.h> > #include <linux/parser.h> > #include <linux/seq_file.h> > +#include <linux/crc32c.h> > #include "xattr.h" > > #define CREATE_TRACE_POINTS > @@ -46,6 +47,45 @@ void _erofs_info(struct super_block *sb, const char > *function, > va_end(args); > } > > +static int erofs_validate_sb_chksum(struct erofs_super_block *dsb, > + struct super_block *sb) erofs_validate_sb_chksum(struct super_block *sb, void *sbdata) Can we pass void *sbdata --- first page(block) instead? > +{ > + u32 disk_chksum = le32_to_cpu(dsb->checksum); > + u32 nblocks = le32_to_cpu(dsb->chksum_blocks); > + u32 crc; > + struct erofs_super_block *dsb2; > + char *buf; > + unsigned int off = 0; > + void *kaddr; > + struct page *page; > + int i, ret = -EINVAL; > + > + buf = kmalloc(nblocks * EROFS_BLKSIZ, GFP_KERNEL); IMO, I think we could just 1) malloc EROFS_BLKSIZ; 2) copy sbdata -> buf; 3) dsb->checksum = 0; 4) crc32c the first copied block; 5) kfree. or some better approach without allocating memory. > + if (!buf) > + goto out; how about erroring out with proper return value? > + for (i = 0; i < nblocks; i++) { > + page = erofs_get_meta_page(sb, i); > + if (IS_ERR(page)) ditto. > + goto out; > + kaddr = kmap_atomic(page); > + (void) memcpy(buf + off, kaddr, EROFS_BLKSIZ); we can call crc32c for multiple times, and no need to get and calc 0-th block again... and no memcpy at all. > + kunmap_atomic(kaddr); > + unlock_page(page); > + /* first page will be released by erofs_read_superblock */ > + if (i != 0) > + put_page(page); > + off += EROFS_BLKSIZ; > + } > + dsb2 = (struct erofs_super_block *)(buf + EROFS_SUPER_OFFSET); > + dsb2->checksum = 0; > + crc = crc32c(0, buf, nblocks * EROFS_BLKSIZ); > + if (crc != disk_chksum) > + goto out; > + ret = 0; > +out: kfree(buf); > + return ret; > +} > + > static void erofs_inode_init_once(void *ptr) > { > struct erofs_inode *vi = ptr; > @@ -109,18 +149,20 @@ static int erofs_read_superblock(struct super_block *sb) > erofs_err(sb, "cannot read erofs superblock"); > return PTR_ERR(page); > } > - > sbi = EROFS_SB(sb); > - > data = kmap_atomic(page); should use kmap() then, because kmalloc() and get_meta_page() can sleep and last for long time. > dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET); > - > ret = -EINVAL; > if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) { > erofs_err(sb, "cannot find valid erofs superblock"); > goto out; > } > - > + if (dsb->feature_compat & EROFS_FEATURE_SB_CHKSUM) { > + if (erofs_validate_sb_chksum(dsb, sb)) { erofs_validate_sb_chksum(sb, data) > + erofs_err(sb, "super block checksum incorrect"); It should be with a proper return value and corresponding messages, see the related discussion: https://lore.kernel.org/r/20190822090541.GA193349@architecture4/ Thanks, Gao Xiang > + goto out; > + } > + } > blkszbits = dsb->blkszbits; > /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */ > if (blkszbits != LOG_BLOCK_SIZE) { > -- > 2.9.3 >
