Andreas, Johann,
thanks a lot for sending those patches! From a previous review I still
remember ext2fs_mmp_read(), see below.
I will look through the other parts later on.
+errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
+{
+ struct mmp_struct *mmp_cmp;
+ errcode_t retval = 0;
+
+ if ((mmp_blk<= fs->super->s_first_data_block) ||
+ (mmp_blk>= fs->super->s_blocks_count))
+ return EXT2_ET_MMP_BAD_BLOCK;
+
+ if (fs->mmp_cmp == NULL) {
+ /* O_DIRECT in linux 2.4: page aligned
+ * O_DIRECT in linux 2.6: sector aligned
+ * A filesystem cannot be created with blocksize< sector size,
+ * or with blocksize> page_size. */
+ int bufsize = fs->blocksize;
+
+ if (bufsize< mmp_pagesize())
+ bufsize = mmp_pagesize();
+ retval = ext2fs_get_memalign(bufsize, bufsize,&fs->mmp_cmp);
+ if (retval)
+ return retval;
+ }
+
+ /* ext2fs_open reserves fd0,1,2 to avoid stdio collision */
+ if (fs->mmp_fd<= 0) {
+ fs->mmp_fd = open(fs->device_name, O_RDWR | O_DIRECT);
+ if (fs->mmp_fd< 0) {
+ retval = EXT2_ET_MMP_OPEN_DIRECT;
+ goto out;
+ }
+ }
+
+ if (ext2fs_llseek(fs->mmp_fd, mmp_blk * fs->blocksize, SEEK_SET) !=
+ mmp_blk * fs->blocksize) {
+ retval = EXT2_ET_LLSEEK_FAILED;
+ goto out;
+ }
+
+ if (read(fs->mmp_fd, fs->mmp_cmp, fs->blocksize) != fs->blocksize) {
+ retval = EXT2_ET_SHORT_READ;
+ goto out;
+ }
While ext2fs_llseek() and read() works fine, I still wonder why the code
does not use io_channel_read_blk64() here, similarly as
io_channel_write_blk64() write in ext2fs_mmp_write().
+
+ mmp_cmp = fs->mmp_cmp;
+#ifdef EXT2FS_ENABLE_SWAPFS
+ if (fs->flags& EXT2_FLAG_SWAP_BYTES)
+ ext2fs_swap_mmp(mmp_cmp);
+#endif
+
+ if (buf != NULL&& buf != fs->mmp_cmp)
+ memcpy(buf, fs->mmp_cmp, fs->blocksize);
+
+ if (mmp_cmp->mmp_magic != EXT4_MMP_MAGIC) {
+ retval = EXT2_ET_MMP_MAGIC_INVALID;
+ goto out;
+ }
+
+out:
+ return retval;
+}
+
+errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
+{
+ struct mmp_struct *mmp_s = buf;
+ struct timeval tv;
+ errcode_t retval = 0;
+
+ gettimeofday(&tv, 0);
+ mmp_s->mmp_time = tv.tv_sec;
+ fs->mmp_last_written = tv.tv_sec;
+
+ if (fs->super->s_mmp_block< fs->super->s_first_data_block ||
+ fs->super->s_mmp_block> ext2fs_blocks_count(fs->super))
+ return EXT2_ET_MMP_BAD_BLOCK;
+
+#ifdef EXT2FS_ENABLE_SWAPFS
+ if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
+ ext2fs_swap_mmp(mmp_s);
+#endif
+
+ /* I was tempted to make this use O_DIRECT and the mmp_fd, but
+ * this caused no end of grief, while leaving it as-is works. */
+ retval = io_channel_write_blk64(fs->io, mmp_blk, -fs->blocksize, buf);
+
+#ifdef EXT2FS_ENABLE_SWAPFS
+ if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
+ ext2fs_swap_mmp(mmp_s);
+#endif
+
+ /* Make sure the block gets to disk quickly */
+ io_channel_flush(fs->io);
+ return retval;
+}
Thanks,
Bernd
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