From d8a2bcf564728cc38b138fed18cd89b097493e75 Mon Sep 17 00:00:00 2001 From: Vladimir 'phcoder' Serbinenko Date: Fri, 15 Apr 2011 21:42:29 +0200 Subject: [PATCH] contiguous read --- grub-core/kern/disk.c | 296 +++++++++++++++++++++++++----------------- 1 file changed, 178 insertions(+), 118 deletions(-) diff --git a/grub-core/kern/disk.c b/grub-core/kern/disk.c index af56527ad..5439a02f6 100644 --- a/grub-core/kern/disk.c +++ b/grub-core/kern/disk.c @@ -398,13 +398,93 @@ transform_sector (grub_disk_t disk, grub_disk_addr_t sector) return sector >> (disk->log_sector_size - GRUB_DISK_SECTOR_BITS); } +/* Small read (less than cache size and not pass across cache unit boundaries). + sector is already adjusted and is divisible by cache unit size. + */ +static grub_err_t +grub_disk_read_small (grub_disk_t disk, grub_disk_addr_t sector, + grub_off_t offset, grub_size_t size, void *buf) +{ + char *data; + char *tmp_buf; + + /* Fetch the cache. */ + data = grub_disk_cache_fetch (disk->dev->id, disk->id, sector); + if (data) + { + /* Just copy it! */ + grub_memcpy (buf, data + offset, size); + grub_disk_cache_unlock (disk->dev->id, disk->id, sector); + return GRUB_ERR_NONE; + } + + /* Allocate a temporary buffer. */ + tmp_buf = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS); + if (! tmp_buf) + return grub_errno; + + /* Otherwise read data from the disk actually. */ + if (disk->total_sectors == GRUB_DISK_SIZE_UNKNOWN + || sector + GRUB_DISK_CACHE_SIZE + < (disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS))) + { + grub_err_t err; + err = (disk->dev->read) (disk, transform_sector (disk, sector), + 1 << (GRUB_DISK_CACHE_BITS + + GRUB_DISK_SECTOR_BITS + - disk->log_sector_size), tmp_buf); + if (!err) + { + /* Copy it and store it in the disk cache. */ + grub_memcpy (buf, tmp_buf + offset, size); + grub_disk_cache_store (disk->dev->id, disk->id, + sector, tmp_buf); + grub_free (tmp_buf); + return GRUB_ERR_NONE; + } + } + + grub_errno = GRUB_ERR_NONE; + + { + /* Uggh... Failed. Instead, just read necessary data. */ + unsigned num; + grub_disk_addr_t aligned_sector; + + sector += (offset >> GRUB_DISK_SECTOR_BITS); + offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1); + aligned_sector = (sector & ~((1 << (disk->log_sector_size + - GRUB_DISK_SECTOR_BITS)) + - 1)); + offset += ((sector - aligned_sector) << GRUB_DISK_SECTOR_BITS); + num = ((size + offset + (1 << (disk->log_sector_size)) + - 1) >> (disk->log_sector_size)); + + tmp_buf = grub_malloc (num << disk->log_sector_size); + if (!tmp_buf) + return grub_errno; + + if ((disk->dev->read) (disk, transform_sector (disk, aligned_sector), + num, tmp_buf)) + { + grub_error_push (); + grub_dprintf ("disk", "%s read failed\n", disk->name); + grub_error_pop (); + return grub_errno; + } + grub_memcpy (buf, tmp_buf + offset, size); + return GRUB_ERR_NONE; + } +} + /* Read data from the disk. */ grub_err_t grub_disk_read (grub_disk_t disk, grub_disk_addr_t sector, grub_off_t offset, grub_size_t size, void *buf) { - char *tmp_buf; - unsigned real_offset; + grub_off_t real_offset; + grub_disk_addr_t real_sector; + grub_size_t real_size; /* First of all, check if the region is within the disk. */ if (grub_disk_adjust_range (disk, §or, &offset, size) != GRUB_ERR_NONE) @@ -416,138 +496,118 @@ grub_disk_read (grub_disk_t disk, grub_disk_addr_t sector, return grub_errno; } + real_sector = sector; real_offset = offset; + real_size = size; - /* Allocate a temporary buffer. */ - tmp_buf = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS); - if (! tmp_buf) - return grub_errno; - - /* Until SIZE is zero... */ - while (size) + /* First read until first cache boundary. */ + if (offset || (sector & (GRUB_DISK_CACHE_SIZE - 1))) { - char *data; grub_disk_addr_t start_sector; - grub_size_t len; grub_size_t pos; + grub_err_t err; + grub_size_t len; - /* For reading bulk data. */ start_sector = sector & ~(GRUB_DISK_CACHE_SIZE - 1); pos = (sector - start_sector) << GRUB_DISK_SECTOR_BITS; len = ((GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS) - - pos - real_offset); + - pos - offset); if (len > size) len = size; - - /* Fetch the cache. */ - data = grub_disk_cache_fetch (disk->dev->id, disk->id, start_sector); - if (data) - { - /* Just copy it! */ - grub_memcpy (buf, data + pos + real_offset, len); - grub_disk_cache_unlock (disk->dev->id, disk->id, start_sector); - } - else - { - /* Otherwise read data from the disk actually. */ - if ((disk->total_sectors != GRUB_DISK_SIZE_UNKNOWN - && start_sector + GRUB_DISK_CACHE_SIZE - > (disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS))) - || (disk->dev->read) (disk, transform_sector (disk, start_sector), - 1 << (GRUB_DISK_CACHE_BITS - + GRUB_DISK_SECTOR_BITS - - disk->log_sector_size), tmp_buf) - != GRUB_ERR_NONE) - { - /* Uggh... Failed. Instead, just read necessary data. */ - unsigned num; - char *p; - grub_disk_addr_t aligned_sector; - - grub_errno = GRUB_ERR_NONE; - - aligned_sector = (sector & ~((1 << (disk->log_sector_size - - GRUB_DISK_SECTOR_BITS)) - - 1)); - real_offset += ((sector - aligned_sector) - << GRUB_DISK_SECTOR_BITS); - num = ((size + real_offset + (1 << (disk->log_sector_size)) - - 1) >> (disk->log_sector_size)); - - p = grub_realloc (tmp_buf, num << disk->log_sector_size); - if (!p) - goto finish; - - tmp_buf = p; - - if ((disk->dev->read) (disk, transform_sector (disk, - aligned_sector), - num, tmp_buf)) - { - grub_error_push (); - grub_dprintf ("disk", "%s read failed\n", disk->name); - grub_error_pop (); - goto finish; - } - - grub_memcpy (buf, tmp_buf + real_offset, size); - - /* Call the read hook, if any. */ - if (disk->read_hook) - while (size) - { - grub_size_t to_read = (size > GRUB_DISK_SECTOR_SIZE) ? GRUB_DISK_SECTOR_SIZE : size; - (disk->read_hook) (sector, real_offset, - to_read); - if (grub_errno != GRUB_ERR_NONE) - goto finish; - - sector++; - size -= to_read - real_offset; - real_offset = 0; - } - - /* This must be the end. */ - goto finish; - } - - /* Copy it and store it in the disk cache. */ - grub_memcpy (buf, tmp_buf + pos + real_offset, len); - grub_disk_cache_store (disk->dev->id, disk->id, - start_sector, tmp_buf); - } - - /* Call the read hook, if any. */ - if (disk->read_hook) - { - grub_disk_addr_t s = sector; - grub_size_t l = len; - - while (l) - { - (disk->read_hook) (s, real_offset, - ((l > GRUB_DISK_SECTOR_SIZE) - ? GRUB_DISK_SECTOR_SIZE - : l)); - - if (l < GRUB_DISK_SECTOR_SIZE - real_offset) - break; - - s++; - l -= GRUB_DISK_SECTOR_SIZE - real_offset; - real_offset = 0; - } - } - - sector = start_sector + GRUB_DISK_CACHE_SIZE; + err = grub_disk_read_small (disk, start_sector, + offset + pos, len, buf); + if (err) + return err; buf = (char *) buf + len; size -= len; - real_offset = 0; + offset += len; + sector += (offset >> GRUB_DISK_SECTOR_BITS); + offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1); } - finish: + /* Until SIZE is zero... */ + while (size >= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS)) + { + char *data = NULL; + grub_disk_addr_t agglomerate; + grub_err_t err; - grub_free (tmp_buf); + /* agglomerate read until we find a first cached entry. */ + for (agglomerate = 0; agglomerate + < (size >> (GRUB_DISK_SECTOR_BITS + GRUB_DISK_CACHE_BITS)); + agglomerate++) + { + data = grub_disk_cache_fetch (disk->dev->id, disk->id, + sector + (agglomerate + << GRUB_DISK_CACHE_BITS)); + if (data) + break; + } + + if (agglomerate) + { + grub_disk_addr_t i; + + err = (disk->dev->read) (disk, transform_sector (disk, sector), + agglomerate << (GRUB_DISK_CACHE_BITS + + GRUB_DISK_SECTOR_BITS + - disk->log_sector_size), + buf); + if (err) + return err; + + for (i = 0; i < agglomerate; i ++) + grub_disk_cache_store (disk->dev->id, disk->id, + sector + (i << GRUB_DISK_CACHE_BITS), + (char *) buf + + (i << (GRUB_DISK_CACHE_BITS + + GRUB_DISK_SECTOR_BITS))); + + sector += agglomerate << GRUB_DISK_CACHE_BITS; + size -= agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS); + buf = (char *) buf + + (agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS)); + } + + if (data) + { + grub_memcpy (buf, data, GRUB_DISK_CACHE_SIZE); + sector += GRUB_DISK_CACHE_SIZE; + buf = (char *) buf + (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS); + size -= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS); + grub_disk_cache_unlock (disk->dev->id, disk->id, + sector + (agglomerate + << GRUB_DISK_CACHE_BITS)); + } + } + + /* And now read the last part. */ + if (size) + { + grub_err_t err; + err = grub_disk_read_small (disk, sector, 0, size, buf); + if (err) + return err; + } + + /* Call the read hook, if any. */ + if (disk->read_hook) + { + grub_disk_addr_t s = real_sector; + grub_size_t l = real_size; + grub_off_t o = real_offset; + + while (l) + { + (disk->read_hook) (s, o, + ((l > GRUB_DISK_SECTOR_SIZE) + ? GRUB_DISK_SECTOR_SIZE + : l)); + s++; + l -= GRUB_DISK_SECTOR_SIZE - o; + o = 0; + } + } return grub_errno; }