diff options
| -rw-r--r-- | fs/dax.c | 241 | ||||
| -rw-r--r-- | fs/ext2/file.c | 34 | ||||
| -rw-r--r-- | include/linux/fs.h | 4 | ||||
| -rw-r--r-- | mm/filemap_xip.c | 206 |
4 files changed, 276 insertions, 209 deletions
@@ -19,9 +19,13 @@ #include <linux/buffer_head.h> #include <linux/fs.h> #include <linux/genhd.h> +#include <linux/highmem.h> +#include <linux/memcontrol.h> +#include <linux/mm.h> #include <linux/mutex.h> #include <linux/sched.h> #include <linux/uio.h> +#include <linux/vmstat.h> int dax_clear_blocks(struct inode *inode, sector_t block, long size) { @@ -221,3 +225,240 @@ ssize_t dax_do_io(int rw, struct kiocb *iocb, struct inode *inode, return retval; } EXPORT_SYMBOL_GPL(dax_do_io); + +/* + * The user has performed a load from a hole in the file. Allocating + * a new page in the file would cause excessive storage usage for + * workloads with sparse files. We allocate a page cache page instead. + * We'll kick it out of the page cache if it's ever written to, + * otherwise it will simply fall out of the page cache under memory + * pressure without ever having been dirtied. + */ +static int dax_load_hole(struct address_space *mapping, struct page *page, + struct vm_fault *vmf) +{ + unsigned long size; + struct inode *inode = mapping->host; + if (!page) + page = find_or_create_page(mapping, vmf->pgoff, + GFP_KERNEL | __GFP_ZERO); + if (!page) + return VM_FAULT_OOM; + /* Recheck i_size under page lock to avoid truncate race */ + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (vmf->pgoff >= size) { + unlock_page(page); + page_cache_release(page); + return VM_FAULT_SIGBUS; + } + + vmf->page = page; + return VM_FAULT_LOCKED; +} + +static int copy_user_bh(struct page *to, struct buffer_head *bh, + unsigned blkbits, unsigned long vaddr) +{ + void *vfrom, *vto; + if (dax_get_addr(bh, &vfrom, blkbits) < 0) + return -EIO; + vto = kmap_atomic(to); + copy_user_page(vto, vfrom, vaddr, to); + kunmap_atomic(vto); + return 0; +} + +static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + 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; + unsigned long pfn; + pgoff_t size; + int error; + + i_mmap_lock_read(mapping); + + /* + * Check truncate didn't happen while we were allocating a block. + * If it did, this block may or may not be still allocated to the + * file. We can't tell the filesystem to free it because we can't + * take i_mutex here. In the worst case, the file still has blocks + * allocated past the end of the file. + */ + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (unlikely(vmf->pgoff >= size)) { + error = -EIO; + goto out; + } + + error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size); + if (error < 0) + goto out; + if (error < PAGE_SIZE) { + error = -EIO; + goto out; + } + + if (buffer_unwritten(bh) || buffer_new(bh)) + clear_page(addr); + + 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) +{ + struct file *file = vma->vm_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct page *page; + struct buffer_head bh; + unsigned long vaddr = (unsigned long)vmf->virtual_address; + unsigned blkbits = inode->i_blkbits; + sector_t block; + pgoff_t size; + int error; + int major = 0; + + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (vmf->pgoff >= size) + return VM_FAULT_SIGBUS; + + memset(&bh, 0, sizeof(bh)); + block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits); + bh.b_size = PAGE_SIZE; + + repeat: + page = find_get_page(mapping, vmf->pgoff); + if (page) { + if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { + page_cache_release(page); + return VM_FAULT_RETRY; + } + if (unlikely(page->mapping != mapping)) { + unlock_page(page); + page_cache_release(page); + goto repeat; + } + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (unlikely(vmf->pgoff >= size)) { + /* + * We have a struct page covering a hole in the file + * from a read fault and we've raced with a truncate + */ + error = -EIO; + goto unlock_page; + } + } + + error = get_block(inode, block, &bh, 0); + if (!error && (bh.b_size < PAGE_SIZE)) + error = -EIO; /* fs corruption? */ + if (error) + goto unlock_page; + + if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) { + if (vmf->flags & FAULT_FLAG_WRITE) { + error = get_block(inode, block, &bh, 1); + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + major = VM_FAULT_MAJOR; + if (!error && (bh.b_size < PAGE_SIZE)) + error = -EIO; + if (error) + goto unlock_page; + } else { + return dax_load_hole(mapping, page, vmf); + } + } + + if (vmf->cow_page) { + struct page *new_page = vmf->cow_page; + if (buffer_written(&bh)) + error = copy_user_bh(new_page, &bh, blkbits, vaddr); + else + clear_user_highpage(new_page, vaddr); + if (error) + goto unlock_page; + vmf->page = page; + if (!page) { + i_mmap_lock_read(mapping); + /* Check we didn't race with truncate */ + size = (i_size_read(inode) + PAGE_SIZE - 1) >> + PAGE_SHIFT; + if (vmf->pgoff >= size) { + i_mmap_unlock_read(mapping); + error = -EIO; + goto out; + } + } + return VM_FAULT_LOCKED; + } + + /* Check we didn't race with a read fault installing a new page */ + if (!page && major) + page = find_lock_page(mapping, vmf->pgoff); + + if (page) { + unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, + PAGE_CACHE_SIZE, 0); + delete_from_page_cache(page); + unlock_page(page); + page_cache_release(page); + } + + error = dax_insert_mapping(inode, &bh, vma, vmf); + + out: + if (error == -ENOMEM) + return VM_FAULT_OOM | major; + /* -EBUSY is fine, somebody else faulted on the same PTE */ + if ((error < 0) && (error != -EBUSY)) + return VM_FAULT_SIGBUS | major; + return VM_FAULT_NOPAGE | major; + + unlock_page: + if (page) { + unlock_page(page); + page_cache_release(page); + } + goto out; +} + +/** + * 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 + * + * When a page fault occurs, filesystems may call this helper in their + * fault handler for DAX files. + */ +int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, + get_block_t get_block) +{ + int result; + struct super_block *sb = file_inode(vma->vm_file)->i_sb; + + if (vmf->flags & FAULT_FLAG_WRITE) { + sb_start_pagefault(sb); + file_update_time(vma->vm_file); + } + result = do_dax_fault(vma, vmf, get_block); + if (vmf->flags & FAULT_FLAG_WRITE) + sb_end_pagefault(sb); + + return result; +} +EXPORT_SYMBOL_GPL(dax_fault); diff --git a/fs/ext2/file.c b/fs/ext2/file.c index a247123fd798..a61c93fd9dce 100644 --- a/fs/ext2/file.c +++ b/fs/ext2/file.c @@ -25,6 +25,36 @@ #include "xattr.h" #include "acl.h" +#ifdef CONFIG_EXT2_FS_XIP +static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + return dax_fault(vma, vmf, ext2_get_block); +} + +static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + return dax_mkwrite(vma, vmf, ext2_get_block); +} + +static const struct vm_operations_struct ext2_dax_vm_ops = { + .fault = ext2_dax_fault, + .page_mkwrite = ext2_dax_mkwrite, +}; + +static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma) +{ + if (!IS_DAX(file_inode(file))) + return generic_file_mmap(file, vma); + + file_accessed(file); + vma->vm_ops = &ext2_dax_vm_ops; + vma->vm_flags |= VM_MIXEDMAP; + return 0; +} +#else +#define ext2_file_mmap generic_file_mmap +#endif + /* * Called when filp is released. This happens when all file descriptors * for a single struct file are closed. Note that different open() calls @@ -70,7 +100,7 @@ const struct file_operations ext2_file_operations = { #ifdef CONFIG_COMPAT .compat_ioctl = ext2_compat_ioctl, #endif - .mmap = generic_file_mmap, + .mmap = ext2_file_mmap, .open = dquot_file_open, .release = ext2_release_file, .fsync = ext2_fsync, @@ -89,7 +119,7 @@ const struct file_operations ext2_xip_file_operations = { #ifdef CONFIG_COMPAT .compat_ioctl = ext2_compat_ioctl, #endif - .mmap = xip_file_mmap, + .mmap = ext2_file_mmap, .open = dquot_file_open, .release = ext2_release_file, .fsync = ext2_fsync, diff --git a/include/linux/fs.h b/include/linux/fs.h index 8084934a5676..6bad6d4c579b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -51,6 +51,7 @@ struct swap_info_struct; struct seq_file; struct workqueue_struct; struct iov_iter; +struct vm_fault; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -2590,9 +2591,10 @@ extern int nonseekable_open(struct inode * inode, struct file * filp); ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, struct iov_iter *, loff_t, get_block_t, dio_iodone_t, int flags); int dax_clear_blocks(struct inode *, sector_t block, long size); +int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); +#define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb) #ifdef CONFIG_FS_XIP -extern int xip_file_mmap(struct file * file, struct vm_area_struct * vma); extern int xip_truncate_page(struct address_space *mapping, loff_t from); #else static inline int xip_truncate_page(struct address_space *mapping, loff_t from) diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c index 9c869f402c07..59fb387b2238 100644 --- a/mm/filemap_xip.c +++ b/mm/filemap_xip.c @@ -23,212 +23,6 @@ #include <asm/io.h> /* - * We do use our own empty page to avoid interference with other users - * of ZERO_PAGE(), such as /dev/zero - */ -static DEFINE_MUTEX(xip_sparse_mutex); -static seqcount_t xip_sparse_seq = SEQCNT_ZERO(xip_sparse_seq); -static struct page *__xip_sparse_page; - -/* called under xip_sparse_mutex */ -static struct page *xip_sparse_page(void) -{ - if (!__xip_sparse_page) { - struct page *page = alloc_page(GFP_HIGHUSER | __GFP_ZERO); - - if (page) - __xip_sparse_page = page; - } - return __xip_sparse_page; -} - -/* - * __xip_unmap is invoked from xip_unmap and xip_write - * - * This function walks all vmas of the address_space and unmaps the - * __xip_sparse_page when found at pgoff. - */ -static void __xip_unmap(struct address_space * mapping, unsigned long pgoff) -{ - struct vm_area_struct *vma; - struct page *page; - unsigned count; - int locked = 0; - - count = read_seqcount_begin(&xip_sparse_seq); - - page = __xip_sparse_page; - if (!page) - return; - -retry: - i_mmap_lock_read(mapping); - vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { - pte_t *pte, pteval; - spinlock_t *ptl; - struct mm_struct *mm = vma->vm_mm; - unsigned long address = vma->vm_start + - ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); - - BUG_ON(address < vma->vm_start || address >= vma->vm_end); - pte = page_check_address(page, mm, address, &ptl, 1); - if (pte) { - /* Nuke the page table entry. */ - flush_cache_page(vma, address, pte_pfn(*pte)); - pteval = ptep_clear_flush(vma, address, pte); - page_remove_rmap(page); - dec_mm_counter(mm, MM_FILEPAGES); - BUG_ON(pte_dirty(pteval)); - pte_unmap_unlock(pte, ptl); - /* must invalidate_page _before_ freeing the page */ - mmu_notifier_invalidate_page(mm, address); - page_cache_release(page); - } - } - i_mmap_unlock_read(mapping); - - if (locked) { - mutex_unlock(&xip_sparse_mutex); - } else if (read_seqcount_retry(&xip_sparse_seq, count)) { - mutex_lock(&xip_sparse_mutex); - locked = 1; - goto retry; - } -} - -/* - * xip_fault() is invoked via the vma operations vector for a - * mapped memory region to read in file data during a page fault. - * - * This function is derived from filemap_fault, but used for execute in place - */ -static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf) -{ - struct file *file = vma->vm_file; - struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - pgoff_t size; - void *xip_mem; - unsigned long xip_pfn; - struct page *page; - int error; - - /* XXX: are VM_FAULT_ codes OK? */ -again: - size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - if (vmf->pgoff >= size) - return VM_FAULT_SIGBUS; - - error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0, - &xip_mem, &xip_pfn); - if (likely(!error)) - goto found; - if (error != -ENODATA) - return VM_FAULT_OOM; - - /* sparse block */ - if ((vma->vm_flags & (VM_WRITE | VM_MAYWRITE)) && - (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) && - (!(mapping->host->i_sb->s_flags & MS_RDONLY))) { - int err; - - /* maybe shared writable, allocate new block */ - mutex_lock(&xip_sparse_mutex); - error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 1, - &xip_mem, &xip_pfn); - mutex_unlock(&xip_sparse_mutex); - if (error) - return VM_FAULT_SIGBUS; - /* unmap sparse mappings at pgoff from all other vmas */ - __xip_unmap(mapping, vmf->pgoff); - -found: - /* - * We must recheck i_size under i_mmap_rwsem to prevent races - * with truncation - */ - i_mmap_lock_read(mapping); - size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> - PAGE_CACHE_SHIFT; - if (unlikely(vmf->pgoff >= size)) { - i_mmap_unlock_read(mapping); - return VM_FAULT_SIGBUS; - } - err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, - xip_pfn); - i_mmap_unlock_read(mapping); - if (err == -ENOMEM) - return VM_FAULT_OOM; - /* - * err == -EBUSY is fine, we've raced against another thread - * that faulted-in the same page - */ - if (err != -EBUSY) - BUG_ON(err); - return VM_FAULT_NOPAGE; - } else { - int err, ret = VM_FAULT_OOM; - - mutex_lock(&xip_sparse_mutex); - write_seqcount_begin(&xip_sparse_seq); - error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0, - &xip_mem, &xip_pfn); - if (unlikely(!error)) { - write_seqcount_end(&xip_sparse_seq); - mutex_unlock(&xip_sparse_mutex); - goto again; - } - if (error != -ENODATA) - goto out; - - /* - * We must recheck i_size under i_mmap_rwsem to prevent races - * with truncation - */ - i_mmap_lock_read(mapping); - size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> - PAGE_CACHE_SHIFT; - if (unlikely(vmf->pgoff >= size)) { - ret = VM_FAULT_SIGBUS; - goto unlock; - } - /* not shared and writable, use xip_sparse_page() */ - page = xip_sparse_page(); - if (!page) - goto unlock; - err = vm_insert_page(vma, (unsigned long)vmf->virtual_address, - page); - if (err == -ENOMEM) - goto unlock; - - ret = VM_FAULT_NOPAGE; -unlock: - i_mmap_unlock_read(mapping); -out: - write_seqcount_end(&xip_sparse_seq); - mutex_unlock(&xip_sparse_mutex); - - return ret; - } -} - -static const struct vm_operations_struct xip_file_vm_ops = { - .fault = xip_file_fault, - .page_mkwrite = filemap_page_mkwrite, -}; - -int xip_file_mmap(struct file * file, struct vm_area_struct * vma) -{ - BUG_ON(!file->f_mapping->a_ops->get_xip_mem); - - file_accessed(file); - vma->vm_ops = &xip_file_vm_ops; - vma->vm_flags |= VM_MIXEDMAP; - return 0; -} -EXPORT_SYMBOL_GPL(xip_file_mmap); - -/* * truncate a page used for execute in place * functionality is analog to block_truncate_page but does use get_xip_mem * to get the page instead of page cache |