From b4caecd48005fbed3949dde6c1cb233142fd69e9 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 14 Jan 2015 10:42:32 +0100 Subject: fs: introduce f_op->mmap_capabilities for nommu mmap support Since "BDI: Provide backing device capability information [try #3]" the backing_dev_info structure also provides flags for the kind of mmap operation available in a nommu environment, which is entirely unrelated to it's original purpose. Introduce a new nommu-only file operation to provide this information to the nommu mmap code instead. Splitting this from the backing_dev_info structure allows to remove lots of backing_dev_info instance that aren't otherwise needed, and entirely gets rid of the concept of providing a backing_dev_info for a character device. It also removes the need for the mtd_inodefs filesystem. Signed-off-by: Christoph Hellwig Reviewed-by: Tejun Heo Acked-by: Brian Norris Signed-off-by: Jens Axboe --- mm/nommu.c | 69 +++++++++++++++++++++++++++----------------------------------- 1 file changed, 30 insertions(+), 39 deletions(-) (limited to 'mm/nommu.c') diff --git a/mm/nommu.c b/mm/nommu.c index b51eadf6d952..13af96f35a4b 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -946,9 +946,6 @@ static int validate_mmap_request(struct file *file, return -EOVERFLOW; if (file) { - /* validate file mapping requests */ - struct address_space *mapping; - /* files must support mmap */ if (!file->f_op->mmap) return -ENODEV; @@ -957,28 +954,22 @@ static int validate_mmap_request(struct file *file, * - we support chardevs that provide their own "memory" * - we support files/blockdevs that are memory backed */ - mapping = file->f_mapping; - if (!mapping) - mapping = file_inode(file)->i_mapping; - - capabilities = 0; - if (mapping && mapping->backing_dev_info) - capabilities = mapping->backing_dev_info->capabilities; - - if (!capabilities) { + if (file->f_op->mmap_capabilities) { + capabilities = file->f_op->mmap_capabilities(file); + } else { /* no explicit capabilities set, so assume some * defaults */ switch (file_inode(file)->i_mode & S_IFMT) { case S_IFREG: case S_IFBLK: - capabilities = BDI_CAP_MAP_COPY; + capabilities = NOMMU_MAP_COPY; break; case S_IFCHR: capabilities = - BDI_CAP_MAP_DIRECT | - BDI_CAP_READ_MAP | - BDI_CAP_WRITE_MAP; + NOMMU_MAP_DIRECT | + NOMMU_MAP_READ | + NOMMU_MAP_WRITE; break; default: @@ -989,9 +980,9 @@ static int validate_mmap_request(struct file *file, /* eliminate any capabilities that we can't support on this * device */ if (!file->f_op->get_unmapped_area) - capabilities &= ~BDI_CAP_MAP_DIRECT; + capabilities &= ~NOMMU_MAP_DIRECT; if (!file->f_op->read) - capabilities &= ~BDI_CAP_MAP_COPY; + capabilities &= ~NOMMU_MAP_COPY; /* The file shall have been opened with read permission. */ if (!(file->f_mode & FMODE_READ)) @@ -1010,29 +1001,29 @@ static int validate_mmap_request(struct file *file, if (locks_verify_locked(file)) return -EAGAIN; - if (!(capabilities & BDI_CAP_MAP_DIRECT)) + if (!(capabilities & NOMMU_MAP_DIRECT)) return -ENODEV; /* we mustn't privatise shared mappings */ - capabilities &= ~BDI_CAP_MAP_COPY; + capabilities &= ~NOMMU_MAP_COPY; } else { /* we're going to read the file into private memory we * allocate */ - if (!(capabilities & BDI_CAP_MAP_COPY)) + if (!(capabilities & NOMMU_MAP_COPY)) return -ENODEV; /* we don't permit a private writable mapping to be * shared with the backing device */ if (prot & PROT_WRITE) - capabilities &= ~BDI_CAP_MAP_DIRECT; + capabilities &= ~NOMMU_MAP_DIRECT; } - if (capabilities & BDI_CAP_MAP_DIRECT) { - if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || - ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || - ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) + if (capabilities & NOMMU_MAP_DIRECT) { + if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) || + ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) || + ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC)) ) { - capabilities &= ~BDI_CAP_MAP_DIRECT; + capabilities &= ~NOMMU_MAP_DIRECT; if (flags & MAP_SHARED) { printk(KERN_WARNING "MAP_SHARED not completely supported on !MMU\n"); @@ -1049,21 +1040,21 @@ static int validate_mmap_request(struct file *file, } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { /* handle implication of PROT_EXEC by PROT_READ */ if (current->personality & READ_IMPLIES_EXEC) { - if (capabilities & BDI_CAP_EXEC_MAP) + if (capabilities & NOMMU_MAP_EXEC) prot |= PROT_EXEC; } } else if ((prot & PROT_READ) && (prot & PROT_EXEC) && - !(capabilities & BDI_CAP_EXEC_MAP) + !(capabilities & NOMMU_MAP_EXEC) ) { /* backing file is not executable, try to copy */ - capabilities &= ~BDI_CAP_MAP_DIRECT; + capabilities &= ~NOMMU_MAP_DIRECT; } } else { /* anonymous mappings are always memory backed and can be * privately mapped */ - capabilities = BDI_CAP_MAP_COPY; + capabilities = NOMMU_MAP_COPY; /* handle PROT_EXEC implication by PROT_READ */ if ((prot & PROT_READ) && @@ -1095,7 +1086,7 @@ static unsigned long determine_vm_flags(struct file *file, vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); /* vm_flags |= mm->def_flags; */ - if (!(capabilities & BDI_CAP_MAP_DIRECT)) { + if (!(capabilities & NOMMU_MAP_DIRECT)) { /* attempt to share read-only copies of mapped file chunks */ vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; if (file && !(prot & PROT_WRITE)) @@ -1104,7 +1095,7 @@ static unsigned long determine_vm_flags(struct file *file, /* overlay a shareable mapping on the backing device or inode * if possible - used for chardevs, ramfs/tmpfs/shmfs and * romfs/cramfs */ - vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); + vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS); if (flags & MAP_SHARED) vm_flags |= VM_SHARED; } @@ -1157,7 +1148,7 @@ static int do_mmap_private(struct vm_area_struct *vma, * shared mappings on devices or memory * - VM_MAYSHARE will be set if it may attempt to share */ - if (capabilities & BDI_CAP_MAP_DIRECT) { + if (capabilities & NOMMU_MAP_DIRECT) { ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); if (ret == 0) { /* shouldn't return success if we're not sharing */ @@ -1346,7 +1337,7 @@ unsigned long do_mmap_pgoff(struct file *file, if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { /* new mapping is not a subset of the region */ - if (!(capabilities & BDI_CAP_MAP_DIRECT)) + if (!(capabilities & NOMMU_MAP_DIRECT)) goto sharing_violation; continue; } @@ -1385,7 +1376,7 @@ unsigned long do_mmap_pgoff(struct file *file, * - this is the hook for quasi-memory character devices to * tell us the location of a shared mapping */ - if (capabilities & BDI_CAP_MAP_DIRECT) { + if (capabilities & NOMMU_MAP_DIRECT) { addr = file->f_op->get_unmapped_area(file, addr, len, pgoff, flags); if (IS_ERR_VALUE(addr)) { @@ -1397,10 +1388,10 @@ unsigned long do_mmap_pgoff(struct file *file, * the mapping so we'll have to attempt to copy * it */ ret = -ENODEV; - if (!(capabilities & BDI_CAP_MAP_COPY)) + if (!(capabilities & NOMMU_MAP_COPY)) goto error_just_free; - capabilities &= ~BDI_CAP_MAP_DIRECT; + capabilities &= ~NOMMU_MAP_DIRECT; } else { vma->vm_start = region->vm_start = addr; vma->vm_end = region->vm_end = addr + len; @@ -1411,7 +1402,7 @@ unsigned long do_mmap_pgoff(struct file *file, vma->vm_region = region; /* set up the mapping - * - the region is filled in if BDI_CAP_MAP_DIRECT is still set + * - the region is filled in if NOMMU_MAP_DIRECT is still set */ if (file && vma->vm_flags & VM_SHARED) ret = do_mmap_shared_file(vma); 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