Thanks Gao, Let me know when we can work on debug utility OR atleast list out things we want to achieve through the utility. Regarding the superblock checksum calculations, Yes I will dedicate sometime this week for it. will start exploring it.
--Pratik. On Wed, Aug 21, 2019 at 10:26 PM Gao Xiang <[email protected]> wrote: > Hi Pratik, > > On Wed, Aug 21, 2019 at 10:08:08PM +0530, Pratik Shinde wrote: > > Hello Maintainers, > > > > After going through the recent mail thread between linux's filesystem > folks > > on erofs channel, I felt erofs needs an interactive debug utility (like > xfs_db) > > which can be used to examine erofs images & can also be used to inject > errors OR > > fuzzing for testing purpose & dumping different erofs meta data > structures > > for debugging. > > In order to demonstrate above I wrote an experimental patch that simply > dumps > > the superblock of an image after mkfs completes.the full fletch utility > will run > > independently and be able to seek / print / modify any byte of an erofs > image, > > dump structures/lists/directory content of an image. > > Yes, I think we really need that interactive tools, actually I'm stuggling > in > modifing Guifu's erofs-fuse now, we need to add the parsing ability to > "lib/" > first. > > I mean, first, I will add a "fuse" field to "cfg". If it is false, it will > generate a image, or it will parse a image... > And then we need to add parsing logic into "lib/" as well, and use > "if (cfg.fuse)" to differnate whether it should read or write data. > > That is my prelimitary thought.. I will work on this framework in this > weekend. > and then we can work together on it. :) > > p.s. Pratik, if you have some time, could you take some extra time adding > the > super checksum calulation to EROFS? I mean we can add > EROFS_FEATURE_SB_CHKSUM > to the compat superblock field ("features"), and do crc32_le on kernel and > mkfs... > If you dont have time, I will do it later instead... (since we are using > EROFS > on the top of dm-verity, but completing the superblock chksum is also a > good idea.) > > And then we can add block-based verification layer to EROFS, it can be seen > as a hash tree like dm-verity or just simply CRC32 arrays for user to > choise. > > Thanks, > Gao Xiang > > > > > NOTE:This is an experimental patch just to demonstrate the purpose. The > patch > > lacks a lot of things like coding standard, and new code runs in the > context > > of mkfs itself.kindly ignore it. > > > > kindly provide your feedback on this. > > > > Signed-off-by: Pratik Shinde <[email protected]> > > --- > > include/erofs/io.h | 8 ++++++++ > > lib/io.c | 27 +++++++++++++++++++++++++++ > > mkfs/main.c | 36 ++++++++++++++++++++++++++++++++++++ > > 3 files changed, 71 insertions(+) > > > > diff --git a/include/erofs/io.h b/include/erofs/io.h > > index 4b574bd..e91d6ee 100644 > > --- a/include/erofs/io.h > > +++ b/include/erofs/io.h > > @@ -18,6 +18,7 @@ > > > > int dev_open(const char *devname); > > void dev_close(void); > > +int dev_read(void *buf, u64 offset, size_t len); > > int dev_write(const void *buf, u64 offset, size_t len); > > int dev_fillzero(u64 offset, size_t len, bool padding); > > int dev_fsync(void); > > @@ -30,5 +31,12 @@ static inline int blk_write(const void *buf, > erofs_blk_t blkaddr, > > blknr_to_addr(nblocks)); > > } > > > > +static inline int blk_read(void *buf, erofs_blk_t blkaddr, > > + u32 nblocks) > > +{ > > + return dev_read(buf, blknr_to_addr(blkaddr), > > + blknr_to_addr(nblocks)); > > +} > > + > > #endif > > > > diff --git a/lib/io.c b/lib/io.c > > index 15c5a35..87d7d6c 100644 > > --- a/lib/io.c > > +++ b/lib/io.c > > @@ -109,6 +109,33 @@ u64 dev_length(void) > > return erofs_devsz; > > } > > > > +int dev_read(void *buf, u64 offset, size_t len) > > +{ > > + int ret; > > + > > + if (cfg.c_dry_run) > > + return 0; > > + > > + if (!buf) { > > + erofs_err("buf is NULL"); > > + return -EINVAL; > > + } > > + if (offset >= erofs_devsz || len > erofs_devsz || > > + offset > erofs_devsz - len) { > > + erofs_err("read posion[%" PRIu64 ", %zd] is too large > beyond the end of device(%" PRIu64 ").", > > + offset, len, erofs_devsz); > > + return -EINVAL; > > + } > > + > > + ret = pread64(erofs_devfd, buf, len, (off64_t)offset); > > + if (ret != (int)len) { > > + erofs_err("Failed to read data from device - %s:[%" PRIu64 > ", %zd].", > > + erofs_devname, offset, len); > > + return -errno; > > + } > > + return 0; > > +} > > + > > int dev_write(const void *buf, u64 offset, size_t len) > > { > > int ret; > > diff --git a/mkfs/main.c b/mkfs/main.c > > index f127fe1..109486e 100644 > > --- a/mkfs/main.c > > +++ b/mkfs/main.c > > @@ -182,6 +182,41 @@ int erofs_mkfs_update_super_block(struct > erofs_buffer_head *bh, > > return 0; > > } > > > > +void erofs_dump_super(char *img_path) > > +{ > > + struct erofs_super_block *sb; > > + char buf[EROFS_BLKSIZ]; > > + unsigned int blksz; > > + int ret = 0; > > + > > + if (img_path == NULL) { > > + erofs_err("image path cannot be null"); > > + return; > > + } > > + ret = blk_read(buf, 0, 1); > > + if (ret) { > > + erofs_err("error reading super-block structure"); > > + return; > > + } > > + > > + sb = (struct erofs_super_block *)((u8 *)buf + EROFS_SUPER_OFFSET); > > + if (le32_to_cpu(sb->magic) != EROFS_SUPER_MAGIC_V1) { > > + erofs_err("not a erofs image"); > > + return; > > + } > > + > > + erofs_dump("magic: 0x%x\n", le32_to_cpu(sb->magic)); > > + blksz = 1 << sb->blkszbits; > > + erofs_dump("block size: %d\n", blksz); > > + erofs_dump("root inode: %d\n", le32_to_cpu(sb->root_nid)); > > + erofs_dump("inodes: %llu\n", le64_to_cpu(sb->inos)); > > + erofs_dump("build time: %u\n", le32_to_cpu(sb->build_time)); > > + erofs_dump("blocks: %u\n", le32_to_cpu(sb->blocks)); > > + erofs_dump("meta block: %u\n", le32_to_cpu(sb->meta_blkaddr)); > > + erofs_dump("xattr block: %u\n", le32_to_cpu(sb->xattr_blkaddr)); > > + erofs_dump("requirements: 0x%x\n", le32_to_cpu(sb->requirements)); > > +} > > + > > int main(int argc, char **argv) > > { > > int err = 0; > > @@ -268,6 +303,7 @@ int main(int argc, char **argv) > > err = -EIO; > > exit: > > z_erofs_compress_exit(); > > + erofs_dump_super("dummy"); > > dev_close(); > > erofs_exit_configure(); > > > > -- > > 2.9.3 > > >
