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ext2: perform super I/O with contiguous memory

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Issue reported by Antoine Leca.

Change-Id: Ie6f3ab6c1943b0b7ea9d5a68d4c24b92bab17233
This commit is contained in:
David van Moolenbroek 2014-11-09 12:59:39 +00:00
parent f53651de01
commit 92601f58cb
1 changed files with 41 additions and 19 deletions
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60
minix/fs/ext2/super.c
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@ -17,6 +17,7 @@
#include <minix/bdev.h>
#include <machine/param.h>
#include <machine/vmparam.h>
#include <sys/mman.h>
#include "buf.h"
#include "inode.h"
#include "super.h"
@ -74,10 +75,13 @@ register struct super_block *sp; /* pointer to a superblock */
/* group descriptors, sp->s_group_desc points to this. */
static struct group_desc *group_descs;
block_t gd_size; /* group descriptors table size in blocks */
int gdt_position;
static char superblock_buf[1024];
u64_t gdt_position;
size_t off, chunk;
ondisk_superblock = (struct super_block *) superblock_buf;
ondisk_superblock = (struct super_block *)mmap(NULL, SUPER_SIZE_D,
PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
if (ondisk_superblock == MAP_FAILED)
panic("can't allocate buffer for super block");
dev = sp->s_dev; /* save device (will be overwritten by copy) */
if (dev == NO_DEV)
@ -90,10 +94,10 @@ register struct super_block *sp; /* pointer to a superblock */
super_block_offset = opt.block_with_super * 1024;
}
r = bdev_read(dev, ((u64_t)(super_block_offset)), (char*) ondisk_superblock,
sizeof(superblock_buf), BDEV_NOFLAGS);
r = bdev_read(dev, super_block_offset, (char*) ondisk_superblock,
SUPER_SIZE_D, BDEV_NOFLAGS);
if (r != sizeof(superblock_buf))
if (r != SUPER_SIZE_D)
return(EINVAL);
super_copy(sp, ondisk_superblock);
@ -150,7 +154,9 @@ register struct super_block *sp; /* pointer to a superblock */
if(!(group_descs = malloc(gd_size * sizeof(struct group_desc))))
panic("can't allocate group desc array");
if(!(ondisk_group_descs = malloc(gd_size * sizeof(struct group_desc))))
ondisk_group_descs = mmap(NULL, gd_size * sizeof(struct group_desc),
PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
if (ondisk_group_descs == MAP_FAILED)
panic("can't allocate group desc array");
/* s_first_data_block (block number, where superblock is stored)
@ -168,11 +174,18 @@ register struct super_block *sp; /* pointer to a superblock */
gdt_position = (opt.block_with_super + 1) * 1024;
}
r = bdev_read(dev, ((u64_t)(gdt_position)), (char*) ondisk_group_descs,
gd_size, BDEV_NOFLAGS);
if (r != (ssize_t) gd_size) {
printf("Can not read group descriptors\n");
return(EINVAL);
/* The driver requires contiguous memory chunks, so use page granularity. */
for (off = 0; off < gd_size; off += chunk) {
chunk = gd_size - off;
if (chunk > PAGE_SIZE)
chunk = PAGE_SIZE;
r = bdev_read(dev, gdt_position + off,
(char *)ondisk_group_descs + off, chunk, BDEV_NOFLAGS);
if (r != (ssize_t)chunk) {
printf("Can not read group descriptors\n");
return(EINVAL);
}
}
/* TODO: check descriptors we just read */
@ -211,7 +224,8 @@ struct super_block *sp; /* pointer to a superblock */
/* Write a superblock and gdt. */
int r;
block_t gd_size; /* group descriptors table size in blocks */
int gdt_position;
u64_t gdt_position;
size_t off, chunk;
if (sp->s_rd_only)
panic("can't write superblock on read-only filesys.");
@ -221,8 +235,8 @@ struct super_block *sp; /* pointer to a superblock */
super_copy(ondisk_superblock, sp);
r = bdev_write(sp->s_dev, ((u64_t)(super_block_offset)), (char *) sp,
SUPER_SIZE_D, BDEV_NOFLAGS);
r = bdev_write(sp->s_dev, super_block_offset, (char *) sp, SUPER_SIZE_D,
BDEV_NOFLAGS);
if (r != SUPER_SIZE_D)
printf("ext2: Warning, failed to write superblock to the disk!\n");
@ -239,11 +253,19 @@ struct super_block *sp; /* pointer to a superblock */
copy_group_descriptors(ondisk_group_descs, sp->s_group_desc,
sp->s_groups_count);
r = bdev_write(sp->s_dev, ((u64_t)(gdt_position)),
(char*) ondisk_group_descs, gd_size, BDEV_NOFLAGS);
if (r != (ssize_t) gd_size) {
printf("Can not write group descriptors\n");
/* As above. Yes, lame. */
for (off = 0; off < gd_size; off += chunk) {
chunk = gd_size - off;
if (chunk > PAGE_SIZE)
chunk = PAGE_SIZE;
r = bdev_write(sp->s_dev, gdt_position + off,
(char *)ondisk_group_descs + off, chunk, BDEV_NOFLAGS);
if (r != (ssize_t)chunk) {
printf("Can not write group descriptors\n");
}
}
group_descriptors_dirty = 0;
}
}