X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?p=kvmfornfv.git;a=blobdiff_plain;f=kernel%2Ffs%2Fdax.c;h=43671b68220ed968386f5c1ad9067f236fbab67e;hp=6f65f00e58ecdc695284de68b832f3822247f594;hb=e09b41010ba33a20a87472ee821fa407a5b8da36;hpb=f93b97fd65072de626c074dbe099a1fff05ce060 diff --git a/kernel/fs/dax.c b/kernel/fs/dax.c index 6f65f00e5..43671b682 100644 --- a/kernel/fs/dax.c +++ b/kernel/fs/dax.c @@ -17,16 +17,23 @@ #include #include #include +#include #include #include #include #include #include #include +#include #include #include #include +/* + * dax_clear_blocks() is called from within transaction context from XFS, + * and hence this means the stack from this point must follow GFP_NOFS + * semantics for all operations. + */ int dax_clear_blocks(struct inode *inode, sector_t block, long size) { struct block_device *bdev = inode->i_sb->s_bdev; @@ -34,7 +41,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size) might_sleep(); do { - void *addr; + void __pmem *addr; unsigned long pfn; long count; @@ -46,10 +53,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size) unsigned pgsz = PAGE_SIZE - offset_in_page(addr); if (pgsz > count) pgsz = count; - if (pgsz < PAGE_SIZE) - memset(addr, 0, pgsz); - else - clear_page(addr); + clear_pmem(addr, pgsz); addr += pgsz; size -= pgsz; count -= pgsz; @@ -59,26 +63,29 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size) } } while (size); + wmb_pmem(); return 0; } EXPORT_SYMBOL_GPL(dax_clear_blocks); -static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits) +static long dax_get_addr(struct buffer_head *bh, void __pmem **addr, + unsigned blkbits) { unsigned long pfn; sector_t sector = bh->b_blocknr << (blkbits - 9); return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size); } -static void dax_new_buf(void *addr, unsigned size, unsigned first, loff_t pos, - loff_t end) +/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */ +static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first, + loff_t pos, loff_t end) { loff_t final = end - pos + first; /* The final byte of the buffer */ if (first > 0) - memset(addr, 0, first); + clear_pmem(addr, first); if (final < size) - memset(addr + final, 0, size - final); + clear_pmem(addr + final, size - final); } static bool buffer_written(struct buffer_head *bh) @@ -106,17 +113,19 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, loff_t pos = start; loff_t max = start; loff_t bh_max = start; - void *addr; + void __pmem *addr; bool hole = false; + bool need_wmb = false; if (iov_iter_rw(iter) != WRITE) end = min(end, i_size_read(inode)); while (pos < end) { - unsigned len; + size_t len; if (pos == max) { unsigned blkbits = inode->i_blkbits; - sector_t block = pos >> blkbits; + long page = pos >> PAGE_SHIFT; + sector_t block = page << (PAGE_SHIFT - blkbits); unsigned first = pos - (block << blkbits); long size; @@ -145,29 +154,38 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, retval = dax_get_addr(bh, &addr, blkbits); if (retval < 0) break; - if (buffer_unwritten(bh) || buffer_new(bh)) + if (buffer_unwritten(bh) || buffer_new(bh)) { dax_new_buf(addr, retval, first, pos, end); + need_wmb = true; + } addr += first; size = retval - first; } max = min(pos + size, end); } - if (iov_iter_rw(iter) == WRITE) - len = copy_from_iter(addr, max - pos, iter); - else if (!hole) - len = copy_to_iter(addr, max - pos, iter); + if (iov_iter_rw(iter) == WRITE) { + len = copy_from_iter_pmem(addr, max - pos, iter); + need_wmb = true; + } else if (!hole) + len = copy_to_iter((void __force *)addr, max - pos, + iter); else len = iov_iter_zero(max - pos, iter); - if (!len) + if (!len) { + retval = -EFAULT; break; + } pos += len; addr += len; } + if (need_wmb) + wmb_pmem(); + return (pos == start) ? retval : pos - start; } @@ -209,7 +227,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, } /* Protects against truncate */ - inode_dio_begin(inode); + if (!(flags & DIO_SKIP_DIO_COUNT)) + inode_dio_begin(inode); retval = dax_io(inode, iter, pos, end, get_block, &bh); @@ -219,7 +238,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, if ((retval > 0) && end_io) end_io(iocb, pos, retval, bh.b_private); - inode_dio_end(inode); + if (!(flags & DIO_SKIP_DIO_COUNT)) + inode_dio_end(inode); out: return retval; } @@ -258,11 +278,13 @@ static int dax_load_hole(struct address_space *mapping, struct page *page, static int copy_user_bh(struct page *to, struct buffer_head *bh, unsigned blkbits, unsigned long vaddr) { - void *vfrom, *vto; + void __pmem *vfrom; + void *vto; + if (dax_get_addr(bh, &vfrom, blkbits) < 0) return -EIO; vto = kmap_atomic(to); - copy_user_page(vto, vfrom, vaddr, to); + copy_user_page(vto, (void __force *)vfrom, vaddr, to); kunmap_atomic(vto); return 0; } @@ -273,7 +295,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, struct address_space *mapping = inode->i_mapping; sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); unsigned long vaddr = (unsigned long)vmf->virtual_address; - void *addr; + void __pmem *addr; unsigned long pfn; pgoff_t size; int error; @@ -301,22 +323,37 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, goto out; } - if (buffer_unwritten(bh) || buffer_new(bh)) - clear_page(addr); + if (buffer_unwritten(bh) || buffer_new(bh)) { + clear_pmem(addr, PAGE_SIZE); + wmb_pmem(); + } error = vm_insert_mixed(vma, vaddr, pfn); out: i_mmap_unlock_read(mapping); - if (bh->b_end_io) - bh->b_end_io(bh, 1); - return error; } -static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, - get_block_t get_block) +/** + * __dax_fault - handle a page fault on a DAX file + * @vma: The virtual memory area where the fault occurred + * @vmf: The description of the fault + * @get_block: The filesystem method used to translate file offsets to blocks + * @complete_unwritten: The filesystem method used to convert unwritten blocks + * to written so the data written to them is exposed. This is required for + * required by write faults for filesystems that will return unwritten + * extent mappings from @get_block, but it is optional for reads as + * dax_insert_mapping() will always zero unwritten blocks. If the fs does + * not support unwritten extents, the it should pass NULL. + * + * When a page fault occurs, filesystems may call this helper in their + * fault handler for DAX files. __dax_fault() assumes the caller has done all + * the necessary locking for the page fault to proceed successfully. + */ +int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, + get_block_t get_block, dax_iodone_t complete_unwritten) { struct file *file = vma->vm_file; struct address_space *mapping = file->f_mapping; @@ -417,7 +454,23 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, page_cache_release(page); } + /* + * If we successfully insert the new mapping over an unwritten extent, + * we need to ensure we convert the unwritten extent. If there is an + * error inserting the mapping, the filesystem needs to leave it as + * unwritten to prevent exposure of the stale underlying data to + * userspace, but we still need to call the completion function so + * the private resources on the mapping buffer can be released. We + * indicate what the callback should do via the uptodate variable, same + * as for normal BH based IO completions. + */ error = dax_insert_mapping(inode, &bh, vma, vmf); + if (buffer_unwritten(&bh)) { + if (complete_unwritten) + complete_unwritten(&bh, !error); + else + WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE)); + } out: if (error == -ENOMEM) @@ -434,6 +487,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } goto out; } +EXPORT_SYMBOL(__dax_fault); /** * dax_fault - handle a page fault on a DAX file @@ -445,7 +499,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, * fault handler for DAX files. */ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, - get_block_t get_block) + get_block_t get_block, dax_iodone_t complete_unwritten) { int result; struct super_block *sb = file_inode(vma->vm_file)->i_sb; @@ -454,7 +508,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, sb_start_pagefault(sb); file_update_time(vma->vm_file); } - result = do_dax_fault(vma, vmf, get_block); + result = __dax_fault(vma, vmf, get_block, complete_unwritten); if (vmf->flags & FAULT_FLAG_WRITE) sb_end_pagefault(sb); @@ -462,6 +516,188 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } EXPORT_SYMBOL_GPL(dax_fault); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* + * The 'colour' (ie low bits) within a PMD of a page offset. This comes up + * more often than one might expect in the below function. + */ +#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) + +int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, unsigned int flags, get_block_t get_block, + dax_iodone_t complete_unwritten) +{ + struct file *file = vma->vm_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct buffer_head bh; + unsigned blkbits = inode->i_blkbits; + unsigned long pmd_addr = address & PMD_MASK; + bool write = flags & FAULT_FLAG_WRITE; + long length; + void __pmem *kaddr; + pgoff_t size, pgoff; + sector_t block, sector; + unsigned long pfn; + int result = 0; + + /* dax pmd mappings are broken wrt gup and fork */ + if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) + return VM_FAULT_FALLBACK; + + /* Fall back to PTEs if we're going to COW */ + if (write && !(vma->vm_flags & VM_SHARED)) + return VM_FAULT_FALLBACK; + /* If the PMD would extend outside the VMA */ + if (pmd_addr < vma->vm_start) + return VM_FAULT_FALLBACK; + if ((pmd_addr + PMD_SIZE) > vma->vm_end) + return VM_FAULT_FALLBACK; + + pgoff = linear_page_index(vma, pmd_addr); + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (pgoff >= size) + return VM_FAULT_SIGBUS; + /* If the PMD would cover blocks out of the file */ + if ((pgoff | PG_PMD_COLOUR) >= size) + return VM_FAULT_FALLBACK; + + memset(&bh, 0, sizeof(bh)); + block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); + + bh.b_size = PMD_SIZE; + length = get_block(inode, block, &bh, write); + if (length) + return VM_FAULT_SIGBUS; + i_mmap_lock_read(mapping); + + /* + * If the filesystem isn't willing to tell us the length of a hole, + * just fall back to PTEs. Calling get_block 512 times in a loop + * would be silly. + */ + if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) + goto fallback; + + /* + * If we allocated new storage, make sure no process has any + * zero pages covering this hole + */ + if (buffer_new(&bh)) { + i_mmap_unlock_read(mapping); + unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); + i_mmap_lock_read(mapping); + } + + /* + * If a truncate happened while we were allocating blocks, we may + * leave blocks allocated to the file that are beyond EOF. We can't + * take i_mutex here, so just leave them hanging; they'll be freed + * when the file is deleted. + */ + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (pgoff >= size) { + result = VM_FAULT_SIGBUS; + goto out; + } + if ((pgoff | PG_PMD_COLOUR) >= size) + goto fallback; + + if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { + spinlock_t *ptl; + pmd_t entry; + struct page *zero_page = get_huge_zero_page(); + + if (unlikely(!zero_page)) + goto fallback; + + ptl = pmd_lock(vma->vm_mm, pmd); + if (!pmd_none(*pmd)) { + spin_unlock(ptl); + goto fallback; + } + + entry = mk_pmd(zero_page, vma->vm_page_prot); + entry = pmd_mkhuge(entry); + set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); + result = VM_FAULT_NOPAGE; + spin_unlock(ptl); + } else { + sector = bh.b_blocknr << (blkbits - 9); + length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn, + bh.b_size); + if (length < 0) { + result = VM_FAULT_SIGBUS; + goto out; + } + if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) + goto fallback; + + /* + * TODO: teach vmf_insert_pfn_pmd() to support + * 'pte_special' for pmds + */ + if (pfn_valid(pfn)) + goto fallback; + + if (buffer_unwritten(&bh) || buffer_new(&bh)) { + int i; + for (i = 0; i < PTRS_PER_PMD; i++) + clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE); + wmb_pmem(); + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + result |= VM_FAULT_MAJOR; + } + + result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write); + } + + out: + i_mmap_unlock_read(mapping); + + if (buffer_unwritten(&bh)) + complete_unwritten(&bh, !(result & VM_FAULT_ERROR)); + + return result; + + fallback: + count_vm_event(THP_FAULT_FALLBACK); + result = VM_FAULT_FALLBACK; + goto out; +} +EXPORT_SYMBOL_GPL(__dax_pmd_fault); + +/** + * dax_pmd_fault - handle a PMD fault on a DAX file + * @vma: The virtual memory area where the fault occurred + * @vmf: The description of the fault + * @get_block: The filesystem method used to translate file offsets to blocks + * + * When a page fault occurs, filesystems may call this helper in their + * pmd_fault handler for DAX files. + */ +int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, unsigned int flags, get_block_t get_block, + dax_iodone_t complete_unwritten) +{ + int result; + struct super_block *sb = file_inode(vma->vm_file)->i_sb; + + if (flags & FAULT_FLAG_WRITE) { + sb_start_pagefault(sb); + file_update_time(vma->vm_file); + } + result = __dax_pmd_fault(vma, address, pmd, flags, get_block, + complete_unwritten); + if (flags & FAULT_FLAG_WRITE) + sb_end_pagefault(sb); + + return result; +} +EXPORT_SYMBOL_GPL(dax_pmd_fault); +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + /** * dax_pfn_mkwrite - handle first write to DAX page * @vma: The virtual memory area where the fault occurred @@ -516,11 +752,12 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, if (err < 0) return err; if (buffer_written(&bh)) { - void *addr; + void __pmem *addr; err = dax_get_addr(&bh, &addr, inode->i_blkbits); if (err < 0) return err; - memset(addr + offset, 0, length); + clear_pmem(addr + offset, length); + wmb_pmem(); } return 0;