/* * __wt_block_write_off -- * Write a buffer into a block, returning the block's offset, size and * checksum. */ int __wt_block_write_off(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_ITEM *buf, wt_off_t *offsetp, uint32_t *sizep, uint32_t *checksump, bool data_checksum, bool checkpoint_io, bool caller_locked) { WT_DECL_RET; /* * Ensure the page header is in little endian order; this doesn't belong * here, but it's the best place to catch all callers. After the write, * swap values back to native order so callers never see anything other * than their original content. */ __wt_page_header_byteswap(buf->mem); ret = __block_write_off(session, block, buf, offsetp, sizep, checksump, data_checksum, checkpoint_io, caller_locked); __wt_page_header_byteswap(buf->mem); return (ret); }
/* * __wt_block_read_off -- * Read an addr/size pair referenced block into a buffer. */ int __wt_block_read_off(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_ITEM *buf, wt_off_t offset, uint32_t size, uint32_t cksum) { WT_BLOCK_HEADER *blk, swap; size_t bufsize; uint32_t page_cksum; __wt_verbose(session, WT_VERB_READ, "off %" PRIuMAX ", size %" PRIu32 ", cksum %" PRIu32, (uintmax_t)offset, size, cksum); WT_STAT_FAST_CONN_INCR(session, block_read); WT_STAT_FAST_CONN_INCRV(session, block_byte_read, size); /* * Grow the buffer as necessary and read the block. Buffers should be * aligned for reading, but there are lots of buffers (for example, file * cursors have two buffers each, key and value), and it's difficult to * be sure we've found all of them. If the buffer isn't aligned, it's * an easy fix: set the flag and guarantee we reallocate it. (Most of * the time on reads, the buffer memory has not yet been allocated, so * we're not adding any additional processing time.) */ if (F_ISSET(buf, WT_ITEM_ALIGNED)) bufsize = size; else { F_SET(buf, WT_ITEM_ALIGNED); bufsize = WT_MAX(size, buf->memsize + 10); } WT_RET(__wt_buf_init(session, buf, bufsize)); WT_RET(__wt_read(session, block->fh, offset, size, buf->mem)); buf->size = size; /* * We incrementally read through the structure before doing a checksum, * do little- to big-endian handling early on, and then select from the * original or swapped structure as needed. */ blk = WT_BLOCK_HEADER_REF(buf->mem); __wt_block_header_byteswap_copy(blk, &swap); if (swap.cksum == cksum) { blk->cksum = 0; page_cksum = __wt_cksum(buf->mem, F_ISSET(&swap, WT_BLOCK_DATA_CKSUM) ? size : WT_BLOCK_COMPRESS_SKIP); if (page_cksum == cksum) { /* * Swap the page-header as needed; this doesn't belong * here, but it's the best place to catch all callers. */ __wt_page_header_byteswap(buf->mem); return (0); } if (!F_ISSET(session, WT_SESSION_QUIET_CORRUPT_FILE)) __wt_errx(session, "read checksum error for %" PRIu32 "B block at " "offset %" PRIuMAX ": calculated block checksum " "of %" PRIu32 " doesn't match expected checksum " "of %" PRIu32, size, (uintmax_t)offset, page_cksum, cksum); } else if (!F_ISSET(session, WT_SESSION_QUIET_CORRUPT_FILE)) __wt_errx(session, "read checksum error for %" PRIu32 "B block at " "offset %" PRIuMAX ": block header checksum " "of %" PRIu32 " doesn't match expected checksum " "of %" PRIu32, size, (uintmax_t)offset, swap.cksum, cksum); /* Panic if a checksum fails during an ordinary read. */ return (block->verify || F_ISSET(session, WT_SESSION_QUIET_CORRUPT_FILE) ? WT_ERROR : __wt_illegal_value(session, block->name)); }
/* * __wt_block_write_off -- * Write a buffer into a block, returning the block's offset, size and * checksum. */ int __wt_block_write_off(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_ITEM *buf, wt_off_t *offsetp, uint32_t *sizep, uint32_t *cksump, bool data_cksum, bool caller_locked) { WT_BLOCK_HEADER *blk; WT_DECL_RET; WT_FH *fh; size_t align_size; wt_off_t offset; uint32_t cksum; bool local_locked; fh = block->fh; /* * Clear the block header to ensure all of it is initialized, even the * unused fields. */ blk = WT_BLOCK_HEADER_REF(buf->mem); memset(blk, 0, sizeof(*blk)); /* * Swap the page-header as needed; this doesn't belong here, but it's * the best place to catch all callers. */ __wt_page_header_byteswap(buf->mem); /* Buffers should be aligned for writing. */ if (!F_ISSET(buf, WT_ITEM_ALIGNED)) { WT_ASSERT(session, F_ISSET(buf, WT_ITEM_ALIGNED)); WT_RET_MSG(session, EINVAL, "direct I/O check: write buffer incorrectly allocated"); } /* * Align the size to an allocation unit. * * The buffer must be big enough for us to zero to the next allocsize * boundary, this is one of the reasons the btree layer must find out * from the block-manager layer the maximum size of the eventual write. */ align_size = WT_ALIGN(buf->size, block->allocsize); if (align_size > buf->memsize) { WT_ASSERT(session, align_size <= buf->memsize); WT_RET_MSG(session, EINVAL, "buffer size check: write buffer incorrectly allocated"); } if (align_size > UINT32_MAX) { WT_ASSERT(session, align_size <= UINT32_MAX); WT_RET_MSG(session, EINVAL, "buffer size check: write buffer too large to write"); } /* Zero out any unused bytes at the end of the buffer. */ memset((uint8_t *)buf->mem + buf->size, 0, align_size - buf->size); /* * Set the disk size so we don't have to incrementally read blocks * during salvage. */ blk->disk_size = WT_STORE_SIZE(align_size); /* * Update the block's checksum: if our caller specifies, checksum the * complete data, otherwise checksum the leading WT_BLOCK_COMPRESS_SKIP * bytes. The assumption is applications with good compression support * turn off checksums and assume corrupted blocks won't decompress * correctly. However, if compression failed to shrink the block, the * block wasn't compressed, in which case our caller will tell us to * checksum the data to detect corruption. If compression succeeded, * we still need to checksum the first WT_BLOCK_COMPRESS_SKIP bytes * because they're not compressed, both to give salvage a quick test * of whether a block is useful and to give us a test so we don't lose * the first WT_BLOCK_COMPRESS_SKIP bytes without noticing. * * Checksum a little-endian version of the header, and write everything * in little-endian format. The checksum is (potentially) returned in a * big-endian format, swap it into place in a separate step. */ blk->flags = 0; if (data_cksum) F_SET(blk, WT_BLOCK_DATA_CKSUM); blk->cksum = 0; __wt_block_header_byteswap(blk); blk->cksum = cksum = __wt_cksum( buf->mem, data_cksum ? align_size : WT_BLOCK_COMPRESS_SKIP); #ifdef WORDS_BIGENDIAN blk->cksum = __wt_bswap32(blk->cksum); #endif /* Pre-allocate some number of extension structures. */ WT_RET(__wt_block_ext_prealloc(session, 5)); /* * Acquire a lock, if we don't already hold one. * Allocate space for the write, and optionally extend the file (note * the block-extend function may release the lock). * Release any locally acquired lock. */ local_locked = false; if (!caller_locked) { __wt_spin_lock(session, &block->live_lock); local_locked = true; } ret = __wt_block_alloc(session, block, &offset, (wt_off_t)align_size); if (ret == 0) ret = __wt_block_extend( session, block, fh, offset, align_size, &local_locked); if (local_locked) __wt_spin_unlock(session, &block->live_lock); WT_RET(ret); /* Write the block. */ if ((ret = __wt_write(session, fh, offset, align_size, buf->mem)) != 0) { if (!caller_locked) __wt_spin_lock(session, &block->live_lock); WT_TRET(__wt_block_off_free( session, block, offset, (wt_off_t)align_size)); if (!caller_locked) __wt_spin_unlock(session, &block->live_lock); WT_RET(ret); } #ifdef HAVE_SYNC_FILE_RANGE /* * Optionally schedule writes for dirty pages in the system buffer * cache, but only if the current session can wait. */ if (block->os_cache_dirty_max != 0 && (block->os_cache_dirty += align_size) > block->os_cache_dirty_max && __wt_session_can_wait(session)) { block->os_cache_dirty = 0; WT_RET(__wt_fsync_async(session, fh)); } #endif #ifdef HAVE_POSIX_FADVISE /* Optionally discard blocks from the system buffer cache. */ if (block->os_cache_max != 0 && (block->os_cache += align_size) > block->os_cache_max) { block->os_cache = 0; if ((ret = posix_fadvise(fh->fd, (wt_off_t)0, (wt_off_t)0, POSIX_FADV_DONTNEED)) != 0) WT_RET_MSG( session, ret, "%s: posix_fadvise", block->name); } #endif WT_STAT_FAST_CONN_INCR(session, block_write); WT_STAT_FAST_CONN_INCRV(session, block_byte_write, align_size); WT_RET(__wt_verbose(session, WT_VERB_WRITE, "off %" PRIuMAX ", size %" PRIuMAX ", cksum %" PRIu32, (uintmax_t)offset, (uintmax_t)align_size, cksum)); *offsetp = offset; *sizep = WT_STORE_SIZE(align_size); *cksump = cksum; return (0); }