[PATCH] uml: Remove ubd-mmap support

Finally rip out the ubd-mmap code, which turned out to be broken by design.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 3 insertions, 322 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 9a56ff94308d..88f956c34fed 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -55,7 +55,7 @@
 #include "mem_kern.h"
 #include "cow.h"
 
-enum ubd_req { UBD_READ, UBD_WRITE, UBD_MMAP };
+enum ubd_req { UBD_READ, UBD_WRITE };
 
 struct io_thread_req {
         enum ubd_req op;
@@ -68,8 +68,6 @@ struct io_thread_req {
         unsigned long sector_mask;
         unsigned long long cow_offset;
         unsigned long bitmap_words[2];
-        int map_fd;
-        unsigned long long map_offset;
         int error;
 };
 
@@ -122,10 +120,6 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 
 #define MAX_DEV (8)
 
-/* Changed in early boot */
-static int ubd_do_mmap = 0;
-#define UBD_MMAP_BLOCK_SIZE PAGE_SIZE
-
 static struct block_device_operations ubd_blops = {
         .owner          = THIS_MODULE,
         .open           = ubd_open,
@@ -175,12 +169,6 @@ struct ubd {
         int no_cow;
         struct cow cow;
         struct platform_device pdev;
-
-        int map_writes;
-        int map_reads;
-        int nomap_writes;
-        int nomap_reads;
-        int write_maps;
 };
 
 #define DEFAULT_COW { \
@@ -200,11 +188,6 @@ struct ubd {
         .openflags =            OPEN_FLAGS, \
         .no_cow =               0, \
         .cow =                  DEFAULT_COW, \
-        .map_writes             = 0, \
-        .map_reads              = 0, \
-        .nomap_writes           = 0, \
-        .nomap_reads            = 0, \
-        .write_maps             = 0, \
 }
 
 struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
@@ -314,13 +297,6 @@ static int ubd_setup_common(char *str, int *index_out)
                 int major;
 
                 str++;
-                if(!strcmp(str, "mmap")){
-                        CHOOSE_MODE(printk("mmap not supported by the ubd "
-                                           "driver in tt mode\n"),
-                                    ubd_do_mmap = 1);
-                        return(0);
-                }
-
                 if(!strcmp(str, "sync")){
                         global_openflags = of_sync(global_openflags);
                         return(0);
@@ -524,7 +500,7 @@ static void ubd_handler(void)
 {
         struct io_thread_req req;
         struct request *rq = elv_next_request(ubd_queue);
-        int n, err;
+        int n;
 
         do_ubd = NULL;
         intr_count++;
@@ -538,19 +514,6 @@ static void ubd_handler(void)
                 return;
         }
         
-        if((req.op != UBD_MMAP) &&
-           ((req.offset != ((__u64) (rq->sector)) << 9) ||
-            (req.length != (rq->current_nr_sectors) << 9)))
-                panic("I/O op mismatch");
-        
-        if(req.map_fd != -1){
-                err = physmem_subst_mapping(req.buffer, req.map_fd,
-                                            req.map_offset, 1);
-                if(err)
-                        printk("ubd_handler - physmem_subst_mapping failed, "
-                               "err = %d\n", -err);
-        }
-
         ubd_finish(rq, req.error);
         reactivate_fd(thread_fd, UBD_IRQ);      
         do_ubd_request(ubd_queue);
@@ -583,14 +546,10 @@ static int ubd_file_size(struct ubd *dev, __u64 *size_out)
 
 static void ubd_close(struct ubd *dev)
 {
-        if(ubd_do_mmap)
-                physmem_forget_descriptor(dev->fd);
         os_close_file(dev->fd);
         if(dev->cow.file == NULL)
                 return;
 
-        if(ubd_do_mmap)
-                physmem_forget_descriptor(dev->cow.fd);
         os_close_file(dev->cow.fd);
         vfree(dev->cow.bitmap);
         dev->cow.bitmap = NULL;
@@ -1010,94 +969,13 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
                            req->bitmap_words, bitmap_len);
 }
 
-static int mmap_fd(struct request *req, struct ubd *dev, __u64 offset)
-{
-        __u64 sector;
-        unsigned char *bitmap;
-        int bit, i;
-
-        /* mmap must have been requested on the command line */
-        if(!ubd_do_mmap)
-                return(-1);
-
-        /* The buffer must be page aligned */
-        if(((unsigned long) req->buffer % UBD_MMAP_BLOCK_SIZE) != 0)
-                return(-1);
-
-        /* The request must be a page long */
-        if((req->current_nr_sectors << 9) != PAGE_SIZE)
-                return(-1);
-
-        if(dev->cow.file == NULL)
-                return(dev->fd);
-
-        sector = offset >> 9;
-        bitmap = (unsigned char *) dev->cow.bitmap;
-        bit = ubd_test_bit(sector, bitmap);
-
-        for(i = 1; i < req->current_nr_sectors; i++){
-                if(ubd_test_bit(sector + i, bitmap) != bit)
-                        return(-1);
-        }
-
-        if(bit || (rq_data_dir(req) == WRITE))
-                offset += dev->cow.data_offset;
-
-        /* The data on disk must be page aligned */
-        if((offset % UBD_MMAP_BLOCK_SIZE) != 0)
-                return(-1);
-
-        return(bit ? dev->fd : dev->cow.fd);
-}
-
-static int prepare_mmap_request(struct ubd *dev, int fd, __u64 offset,
-                                struct request *req,
-                                struct io_thread_req *io_req)
-{
-        int err;
-
-        if(rq_data_dir(req) == WRITE){
-                /* Writes are almost no-ops since the new data is already in the
-                 * host page cache
-                 */
-                dev->map_writes++;
-                if(dev->cow.file != NULL)
-                        cowify_bitmap(io_req->offset, io_req->length,
-                                      &io_req->sector_mask, &io_req->cow_offset,
-                                      dev->cow.bitmap, dev->cow.bitmap_offset,
-                                      io_req->bitmap_words,
-                                      dev->cow.bitmap_len);
-        }
-        else {
-                int w;
-
-                if((dev->cow.file != NULL) && (fd == dev->cow.fd))
-                        w = 0;
-                else w = dev->openflags.w;
-
-                if((dev->cow.file != NULL) && (fd == dev->fd))
-                        offset += dev->cow.data_offset;
-
-                err = physmem_subst_mapping(req->buffer, fd, offset, w);
-                if(err){
-                        printk("physmem_subst_mapping failed, err = %d\n",
-                               -err);
-                        return(1);
-                }
-                dev->map_reads++;
-        }
-        io_req->op = UBD_MMAP;
-        io_req->buffer = req->buffer;
-        return(0);
-}
-
 /* Called with ubd_io_lock held */
 static int prepare_request(struct request *req, struct io_thread_req *io_req)
 {
         struct gendisk *disk = req->rq_disk;
         struct ubd *dev = disk->private_data;
         __u64 offset;
-        int len, fd;
+        int len;
 
         if(req->rq_status == RQ_INACTIVE) return(1);
 
@@ -1114,34 +992,12 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 
         io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
         io_req->fds[1] = dev->fd;
-        io_req->map_fd = -1;
         io_req->cow_offset = -1;
         io_req->offset = offset;
         io_req->length = len;
         io_req->error = 0;
         io_req->sector_mask = 0;
 
-        fd = mmap_fd(req, dev, io_req->offset);
-        if(fd > 0){
-                /* If mmapping is otherwise OK, but the first access to the
-                 * page is a write, then it's not mapped in yet.  So we have
-                 * to write the data to disk first, then we can map the disk
-                 * page in and continue normally from there.
-                 */
-                if((rq_data_dir(req) == WRITE) && !is_remapped(req->buffer)){
-                        io_req->map_fd = dev->fd;
-                        io_req->map_offset = io_req->offset +
-                                dev->cow.data_offset;
-                        dev->write_maps++;
-                }
-                else return(prepare_mmap_request(dev, fd, io_req->offset, req,
-                                                 io_req));
-        }
-
-        if(rq_data_dir(req) == READ)
-                dev->nomap_reads++;
-        else dev->nomap_writes++;
-
         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
         io_req->offsets[0] = 0;
         io_req->offsets[1] = dev->cow.data_offset;
@@ -1229,143 +1085,6 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
         return(-EINVAL);
 }
 
-static int ubd_check_remapped(int fd, unsigned long address, int is_write,
-                              __u64 offset)
-{
-        __u64 bitmap_offset;
-        unsigned long new_bitmap[2];
-        int i, err, n;
-
-        /* If it's not a write access, we can't do anything about it */
-        if(!is_write)
-                return(0);
-
-        /* We have a write */
-        for(i = 0; i < sizeof(ubd_dev) / sizeof(ubd_dev[0]); i++){
-                struct ubd *dev = &ubd_dev[i];
-
-                if((dev->fd != fd) && (dev->cow.fd != fd))
-                        continue;
-
-                /* It's a write to a ubd device */
-
-                /* This should be impossible now */
-                if(!dev->openflags.w){
-                        /* It's a write access on a read-only device - probably
-                         * shouldn't happen.  If the kernel is trying to change
-                         * something with no intention of writing it back out,
-                         * then this message will clue us in that this needs
-                         * fixing
-                         */
-                        printk("Write access to mapped page from readonly ubd "
-                               "device %d\n", i);
-                        return(0);
-                }
-
-                /* It's a write to a writeable ubd device - it must be COWed
-                 * because, otherwise, the page would have been mapped in
-                 * writeable
-                 */
-
-                if(!dev->cow.file)
-                        panic("Write fault on writeable non-COW ubd device %d",
-                              i);
-
-                /* It should also be an access to the backing file since the
-                 * COW pages should be mapped in read-write
-                 */
-
-                if(fd == dev->fd)
-                        panic("Write fault on a backing page of ubd "
-                              "device %d\n", i);
-
-                /* So, we do the write, copying the backing data to the COW
-                 * file...
-                 */
-
-                err = os_seek_file(dev->fd, offset + dev->cow.data_offset);
-                if(err < 0)
-                        panic("Couldn't seek to %lld in COW file of ubd "
-                              "device %d, err = %d",
-                              offset + dev->cow.data_offset, i, -err);
-
-                n = os_write_file(dev->fd, (void *) address, PAGE_SIZE);
-                if(n != PAGE_SIZE)
-                        panic("Couldn't copy data to COW file of ubd "
-                              "device %d, err = %d", i, -n);
-
-                /* ... updating the COW bitmap... */
-
-                cowify_bitmap(offset, PAGE_SIZE, NULL, &bitmap_offset,
-                              dev->cow.bitmap, dev->cow.bitmap_offset,
-                              new_bitmap, dev->cow.bitmap_len);
-
-                err = os_seek_file(dev->fd, bitmap_offset);
-                if(err < 0)
-                        panic("Couldn't seek to %lld in COW file of ubd "
-                              "device %d, err = %d", bitmap_offset, i, -err);
-
-                n = os_write_file(dev->fd, new_bitmap, sizeof(new_bitmap));
-                if(n != sizeof(new_bitmap))
-                        panic("Couldn't update bitmap  of ubd device %d, "
-                              "err = %d", i, -n);
-
-                /* Maybe we can map the COW page in, and maybe we can't.  If
-                 * it is a pre-V3 COW file, we can't, since the alignment will
-                 * be wrong.  If it is a V3 or later COW file which has been
-                 * moved to a system with a larger page size, then maybe we
-                 * can't, depending on the exact location of the page.
-                 */
-
-                offset += dev->cow.data_offset;
-
-                /* Remove the remapping, putting the original anonymous page
-                 * back.  If the COW file can be mapped in, that is done.
-                 * Otherwise, the COW page is read in.
-                 */
-
-                if(!physmem_remove_mapping((void *) address))
-                        panic("Address 0x%lx not remapped by ubd device %d",
-                              address, i);
-                if((offset % UBD_MMAP_BLOCK_SIZE) == 0)
-                        physmem_subst_mapping((void *) address, dev->fd,
-                                              offset, 1);
-                else {
-                        err = os_seek_file(dev->fd, offset);
-                        if(err < 0)
-                                panic("Couldn't seek to %lld in COW file of "
-                                      "ubd device %d, err = %d", offset, i,
-                                      -err);
-
-                        n = os_read_file(dev->fd, (void *) address, PAGE_SIZE);
-                        if(n != PAGE_SIZE)
-                                panic("Failed to read page from offset %llx of "
-                                      "COW file of ubd device %d, err = %d",
-                                      offset, i, -n);
-                }
-
-                return(1);
-        }
-
-        /* It's not a write on a ubd device */
-        return(0);
-}
-
-static struct remapper ubd_remapper = {
-        .list   = LIST_HEAD_INIT(ubd_remapper.list),
-        .proc   = ubd_check_remapped,
-};
-
-static int ubd_remapper_setup(void)
-{
-        if(ubd_do_mmap)
-                register_remapper(&ubd_remapper);
-
-        return(0);
-}
-
-__initcall(ubd_remapper_setup);
-
 static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
 {
         struct uml_stat buf1, buf2;
@@ -1568,15 +1287,6 @@ void do_io(struct io_thread_req *req)
         int err;
         __u64 off;
 
-        if(req->op == UBD_MMAP){
-                /* Touch the page to force the host to do any necessary IO to
-                 * get it into memory
-                 */
-                n = *((volatile int *) req->buffer);
-                req->error = update_bitmap(req);
-                return;
-        }
-
         nsectors = req->length / req->sectorsize;
         start = 0;
         do {
diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c
index 9ae2eff0d8f3..1de22d8a313a 100644
--- a/arch/um/kernel/trap_kern.c
+++ b/arch/um/kernel/trap_kern.c
@@ -107,33 +107,6 @@ out_of_memory:
         goto out;
 }
 
-LIST_HEAD(physmem_remappers);
-
-void register_remapper(struct remapper *info)
-{
-        list_add(&info->list, &physmem_remappers);
-}
-
-static int check_remapped_addr(unsigned long address, int is_write)
-{
-        struct remapper *remapper;
-        struct list_head *ele;
-        __u64 offset;
-        int fd;
-
-        fd = phys_mapping(__pa(address), &offset);
-        if(fd == -1)
-                return(0);
-
-        list_for_each(ele, &physmem_remappers){
-                remapper = list_entry(ele, struct remapper, list);
-                if((*remapper->proc)(fd, address, is_write, offset))
-                        return(1);
-        }
-
-        return(0);
-}
-
 /*
  * We give a *copy* of the faultinfo in the regs to segv.
  * This must be done, since nesting SEGVs could overwrite
@@ -152,8 +125,6 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
                 flush_tlb_kernel_vm();
                 return(0);
         }
-        else if(check_remapped_addr(address & PAGE_MASK, is_write))
-                return(0);
         else if(current->mm == NULL)
                 panic("Segfault with no mm");
         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);