On Tue March 28 2006 4:58 pm, Kevin Corry wrote: > On Tue March 28 2006 9:01 am, Alasdair G Kergon wrote: > > A couple of options: > > > > Retain the existing on-disk format exactly, but adjust the offsets and > > sizes used in the reads and writes to avoid the problems (pre-reading > > other data if necessary to extend a write). > > This method seems like it should be easy to implement. We could just extend > the buffer for the disk-header and always read and write both the header > and the log at the same time, and just point lc->clean_bits at the > appropriate offset within that buffer. The log could then remain at offset > 1k, and the version wouldn't have to change. Sorry I haven't had a chance to get back to this in a while. I was finally able to finish up a new patch to fix this bug based on the above suggestions. This patch maintains compatibility with the existing metadata layout by combining the disk-header buffer and clean-bits bitset buffer into a single buffer. -- Kevin Corry kevcorry@xxxxxxxxxx http://www.ibm.com/linux/ http://evms.sourceforge.net/ On-disk logs for dm-mirror devices are currently hard-coded to use 512 byte hard-sector-sizes. This patch fixes dm-log so it will work with devices with non-512-byte hard-sector-sizes. To maintain full compatibility, instead of moving the clean-bits bitset to a different location, this patch removes the separate buffer used for the bitset, and enlarges the disk-header buffer to encompass both the header and the bitset. The I/O routines for the bitset are removed, and the I/O routines for the disk-header now also read/write the bitset. Signed-Off-By: Kevin Corry <kevcorry@xxxxxxxxxx> Index: 2.6.17-rc1/drivers/md/dm-log.c =================================================================== --- 2.6.17-rc1.orig/drivers/md/dm-log.c +++ 2.6.17-rc1/drivers/md/dm-log.c @@ -155,8 +155,6 @@ struct log_c { struct io_region header_location; struct log_header *disk_header; - - struct io_region bits_location; }; /* @@ -241,29 +239,6 @@ static inline int write_header(struct lo } /*---------------------------------------------------------------- - * Bits IO - *--------------------------------------------------------------*/ -static int read_bits(struct log_c *log) -{ - int r; - unsigned long ebits; - - r = dm_io_sync_vm(1, &log->bits_location, READ, - log->clean_bits, &ebits); - if (r) - return r; - - return 0; -} - -static int write_bits(struct log_c *log) -{ - unsigned long ebits; - return dm_io_sync_vm(1, &log->bits_location, WRITE, - log->clean_bits, &ebits); -} - -/*---------------------------------------------------------------- * core log constructor/destructor * * argv contains region_size followed optionally by [no]sync @@ -373,9 +348,11 @@ static int disk_ctr(struct dirty_log *lo unsigned int argc, char **argv) { int r; - size_t size; + size_t size, bitset_size; struct log_c *lc; struct dm_dev *dev; + uint32_t *clean_bits; + unsigned int hardsect_size; if (argc < 2 || argc > 3) { DMWARN("wrong number of arguments to disk mirror log"); @@ -396,26 +373,30 @@ static int disk_ctr(struct dirty_log *lo lc = (struct log_c *) log->context; lc->log_dev = dev; + hardsect_size = ti->limits.hardsect_size; + bitset_size = lc->bitset_uint32_count * sizeof(uint32_t); + /* setup the disk header fields */ lc->header_location.bdev = lc->log_dev->bdev; lc->header_location.sector = 0; - lc->header_location.count = 1; - /* - * We can't read less than this amount, even though we'll - * not be using most of this space. - */ - lc->disk_header = vmalloc(1 << SECTOR_SHIFT); + /* Include both the header and the bitset in one buffer. */ + size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) + bitset_size, + hardsect_size); + lc->header_location.count = size >> SECTOR_SHIFT; + + lc->disk_header = vmalloc(size); if (!lc->disk_header) goto bad; - /* setup the disk bitset fields */ - lc->bits_location.bdev = lc->log_dev->bdev; - lc->bits_location.sector = LOG_OFFSET; - - size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t), - 1 << SECTOR_SHIFT); - lc->bits_location.count = size >> SECTOR_SHIFT; + /* Deallocate the clean_bits buffer that was allocated in core_ctr() + * and point it at the appropriate place in the disk_header buffer. + */ + clean_bits = lc->clean_bits; + lc->clean_bits = (void *)lc->disk_header + (LOG_OFFSET << SECTOR_SHIFT); + memcpy(lc->clean_bits, clean_bits, bitset_size); + vfree(clean_bits); + return 0; bad: @@ -429,6 +410,7 @@ static void disk_dtr(struct dirty_log *l struct log_c *lc = (struct log_c *) log->context; dm_put_device(lc->ti, lc->log_dev); vfree(lc->disk_header); + lc->clean_bits = NULL; core_dtr(log); } @@ -449,16 +431,11 @@ static int disk_resume(struct dirty_log struct log_c *lc = (struct log_c *) log->context; size_t size = lc->bitset_uint32_count * sizeof(uint32_t); - /* read the disk header */ + /* read the disk header and bitset */ r = read_header(lc); if (r) return r; - /* read the bits */ - r = read_bits(lc); - if (r) - return r; - /* set or clear any new bits */ if (lc->sync == NOSYNC) for (i = lc->header.nr_regions; i < lc->region_count; i++) @@ -473,15 +450,10 @@ static int disk_resume(struct dirty_log memcpy(lc->sync_bits, lc->clean_bits, size); lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count); - /* write the bits */ - r = write_bits(lc); - if (r) - return r; - /* set the correct number of regions in the header */ lc->header.nr_regions = lc->region_count; - /* write the new header */ + /* write the new header and bitset */ return write_header(lc); } @@ -518,7 +490,7 @@ static int disk_flush(struct dirty_log * if (!lc->touched) return 0; - r = write_bits(lc); + r = write_header(lc); if (!r) lc->touched = 0; -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
