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VM: readd support for forgetting cached FS blocks

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Not all services involved in block I/O go through VM to access the
blocks they need.  As a result, the blocks in VM may become stale,
possibly causing corruption when the stale copy is restored by a
service that does go through VM later on.  This patch restores support
for forgetting cached blocks that belong to a particular device, and
makes the relevant file systems use this functionality 1) when
requested by VFS through REQ_FLUSH, and 2) upon unmount.

Change-Id: I0758c5ed8fe4b5ba81d432595d2113175776aff8
This commit is contained in:
David van Moolenbroek 2013-09-15 18:55:42 +02:00 committed by Lionel Sambuc
parent df724f2e14
commit b48542d914
15 changed files with 75 additions and 14 deletions
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1
commands/service/parse.c
View file

@ -734,6 +734,7 @@ struct
{ "PROCCTL", VM_PROCCTL },
{ "MAPCACHEPAGE", VM_MAPCACHEPAGE },
{ "SETCACHEPAGE", VM_SETCACHEPAGE },
{ "CLEARCACHE", VM_CLEARCACHE },
{ "VFS_MMAP", VM_VFS_MMAP },
{ "VFS_REPLY", VM_VFS_REPLY },
{ NULL, 0 },

6
etc/system.conf
View file

@ -110,7 +110,7 @@ service mfs
{
ipc ALL_SYS; # All system ipc targets allowed
system BASIC; # Only basic kernel calls allowed
vm MAPCACHEPAGE SETCACHEPAGE;
vm MAPCACHEPAGE SETCACHEPAGE CLEARCACHE;
io NONE; # No I/O range allowed
irq NONE; # No IRQ allowed
sigmgr rs; # Signal manager is RS
@ -137,7 +137,7 @@ service ext2
{
ipc ALL_SYS; # All system ipc targets allowed
system BASIC; # Only basic kernel calls allowed
vm MAPCACHEPAGE SETCACHEPAGE;
vm MAPCACHEPAGE SETCACHEPAGE CLEARCACHE;
io NONE; # No I/O range allowed
irq NONE; # No IRQ allowed
sigmgr rs; # Signal manager is RS
@ -150,7 +150,7 @@ service pfs
{
ipc ALL_SYS; # All system ipc targets allowed
system BASIC; # Only basic kernel calls allowed
vm MAPCACHEPAGE SETCACHEPAGE;
vm MAPCACHEPAGE SETCACHEPAGE CLEARCACHE;
io NONE; # No I/O range allowed
irq NONE; # No IRQ allowed
sigmgr rs; # Signal manager is RS

3
include/minix/com.h
View file

@ -978,6 +978,9 @@
/* To VM: identify cache block in FS */
#define VM_SETCACHEPAGE (VM_RQ_BASE+27)
/* To VM: clear all cache blocks for a device */
#define VM_CLEARCACHE (VM_RQ_BASE+28)
/* To VFS: fields for request from VM. */
# define VFS_VMCALL_REQ m10_i1
# define VFS_VMCALL_FD m10_i2

2
include/minix/vm.h
View file

@ -72,6 +72,8 @@ int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize);
int vm_clear_cache(u32_t dev);
/* flags for vm cache functions */
#define VMMC_FLAGS_LOCKED 0x01 /* someone is updating the flags; don't read/write */
#define VMMC_DIRTY 0x02 /* dirty buffer and it may not be evicted */

2
lib/libminixfs/cache.c
View file

@ -577,6 +577,8 @@ void lmfs_invalidate(
bp->data = NULL;
}
}
vm_clear_cache(device);
}
/*===========================================================================*

14
lib/libsys/vm_cache.c
View file

@ -60,3 +60,17 @@ int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
return vm_cachecall(&m, VM_SETCACHEPAGE, block, dev, dev_offset,
ino, ino_offset, flags, blocksize);
}
int
vm_clear_cache(u32_t dev)
{
message m;
assert(dev != NO_DEV);
memset(&m, 0, sizeof(m));
m.m_u.m_vmmcp.dev = dev;
return _taskcall(VM_PROC_NR, VM_CLEARCACHE, &m);
}

3
servers/ext2/mount.c
View file

@ -241,6 +241,9 @@ int fs_unmount()
/* Close the device the file system lives on. */
bdev_close(fs_dev);
/* Throw all blocks out of the VM cache, to prevent corruption later. */
lmfs_invalidate(fs_dev);
/* Finish off the unmount. */
superblock->s_dev = NO_DEV;
unmountdone = TRUE;

3
servers/mfs/mount.c
View file

@ -187,6 +187,9 @@ int fs_unmount()
/* Close the device the file system lives on. */
bdev_close(fs_dev);
/* Throw out blocks out of the VM cache, to prevent corruption later. */
lmfs_invalidate(fs_dev);
/* Finish off the unmount. */
superblock.s_dev = NO_DEV;
unmountdone = TRUE;

19
servers/vm/cache.c
View file

@ -304,6 +304,25 @@ int cache_freepages(int pages)
return freed;
}
/*
* Remove all pages that are associated with the given device.
*/
void
clear_cache_bydev(dev_t dev)
{
struct cached_page *cp, *ncp;
int h;
for (h = 0; h < HASHSIZE; h++) {
for (cp = cache_hash_bydev[h]; cp != NULL; cp = ncp) {
ncp = cp->hash_next_dev;
if (cp->dev == dev)
rmcache(cp);
}
}
}
void get_stats_info(struct vm_stats_info *vsi)
{
vsi->vsi_cached = cached_pages;

1
servers/vm/main.c
View file

@ -485,6 +485,7 @@ void init_vm(void)
/* Cache blocks. */
CALLMAP(VM_MAPCACHEPAGE, do_mapcache);
CALLMAP(VM_SETCACHEPAGE, do_setcache);
CALLMAP(VM_CLEARCACHE, do_clearcache);
/* getrusage */
CALLMAP(VM_GETRUSAGE, do_getrusage);

14
servers/vm/mem_cache.c
View file

@ -238,3 +238,17 @@ do_setcache(message *msg)
return OK;
}
/*
* A file system wants to invalidate all pages belonging to a certain device.
*/
int
do_clearcache(message *msg)
{
dev_t dev;
dev = msg->m_u.m_vmmcp.dev;
clear_cache_bydev(dev);
return OK;
}

2
servers/vm/proto.h
View file

@ -218,6 +218,7 @@ void shared_setsource(struct vir_region *vr, endpoint_t ep, struct vir_region *s
/* mem_cache.c */
int do_mapcache(message *m);
int do_setcache(message *m);
int do_clearcache(message *m);
/* cache.c */
struct cached_page *find_cached_page_bydev(dev_t dev, u64_t dev_off,
@ -229,6 +230,7 @@ int cache_freepages(int pages);
void get_stats_info(struct vm_stats_info *vsi);
void cache_lru_touch(struct cached_page *hb);
void rmcache(struct cached_page *cp);
void clear_cache_bydev(dev_t dev);
/* vfs.c */
int vfs_request(int reqno, int fd, struct vmproc *vmp, u64_t offset,

15
test/test72.c
View file

@ -224,16 +224,6 @@ panic(const char *fmt, ...)
exit(1);
}
int vm_forgetblock(u64_t id)
{
return ENOSYS;
}
void vm_forgetblocks(void)
{
return;
}
int
vm_info_stats(struct vm_stats_info *vsi)
{
@ -274,6 +264,11 @@ void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
return MAP_FAILED;
}
int vm_clear_cache(u32_t dev)
{
return 0;
}
int
main(int argc, char *argv[])
{

2
test/testvm.c
View file

@ -177,6 +177,8 @@ main(int argc, char *argv[])
writepipe(&info);
vm_clear_cache(MYDEV);
return 0;
}

2
test/testvm.conf
View file

@ -1,7 +1,7 @@
service testvm {
ipc ALL; # All system ipc targets allowed
system BASIC; # Only basic kernel calls allowed
vm MAPCACHEPAGE SETCACHEPAGE;
vm MAPCACHEPAGE SETCACHEPAGE CLEARCACHE;
io NONE; # No I/O range allowed
irq NONE; # No IRQ allowed
sigmgr rs; # Signal manager is RS