Hi Pratik, Some comments as below...
On Tue, Oct 22, 2019 at 09:09:56PM +0530, Pratik Shinde wrote: > Patch for kernel side changes of checksum feature.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 | 3 ++- > fs/erofs/super.c | 33 +++++++++++++++++++++++++++++++++ > 3 files changed, 38 insertions(+), 3 deletions(-) > > diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h > index b1ee565..4d8097a 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_COMPAT_SB_CHKSUM 0x00000001 > > /* 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..cec27ca 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 feature_compat; > unsigned int mount_opt; > }; > > @@ -426,6 +426,7 @@ static inline void z_erofs_exit_zip_subsystem(void) {} > #endif /* !CONFIG_EROFS_FS_ZIP */ > > #define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */ > +#define EFSBADCRC EBADMSG /* Bad crc found */ > > #endif /* __EROFS_INTERNAL_H */ > > diff --git a/fs/erofs/super.c b/fs/erofs/super.c > index 0e36949..9cda72d 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 +47,31 @@ 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) > +{ > + u32 disk_chksum, nblocks, crc = 0; > + void *kaddr; > + struct page *page; > + int i; > + > + disk_chksum = le32_to_cpu(dsb->checksum); > + nblocks = le32_to_cpu(dsb->chksum_blocks); We cannot write the page data directly since the page cache should be kept in sync with ondisk data (or for read-write fs, if it's claimed as uptodated, and it is modified later, you should mark it dirty, and do writeback then, but that is not the erofs case.) > + dsb->checksum = 0; > + for (i = 0; i < nblocks; i++) { > + page = erofs_get_meta_page(sb, i); > + if (IS_ERR(page)) > + return PTR_ERR(page); > + kaddr = kmap(page); Here kmap_atomic(page) is better. what I mean is kmap_atomic() in the caller erofs_read_superblock(), it should be replaced to kmap() instead. > + crc = crc32c(crc, kaddr, EROFS_BLKSIZ); > + kunmap(page); > + unlock_page(page); need put_page(page); I'm not sure whether I explained quite well, but this patch needs something to do. I'm now working on demonstrating new XZ algorithm and releasing erofs-utils v1.0. You can give more tries or I will help later. :-) Thanks, Gao Xiang > + } > + if (crc != disk_chksum) > + return -EFSBADCRC; > + return 0; > +} > + > static void erofs_inode_init_once(void *ptr) > { > struct erofs_inode *vi = ptr; > @@ -121,6 +147,13 @@ static int erofs_read_superblock(struct super_block *sb) > goto out; > } > > + if (dsb->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) { > + ret = erofs_validate_sb_chksum(dsb, sb); > + if (ret < 0) { > + erofs_err(sb, "super block checksum incorrect"); > + goto out; > + } > + } > blkszbits = dsb->blkszbits; > /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */ > if (blkszbits != LOG_BLOCK_SIZE) { > -- > 2.9.3 >
