diff options
Diffstat (limited to 'mm/filemap_xip.c')
| -rw-r--r-- | mm/filemap_xip.c | 65 |
1 files changed, 50 insertions, 15 deletions
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c index 380ab402d711..b5167dfb2f2d 100644 --- a/mm/filemap_xip.c +++ b/mm/filemap_xip.c @@ -15,6 +15,8 @@ #include <linux/rmap.h> #include <linux/mmu_notifier.h> #include <linux/sched.h> +#include <linux/seqlock.h> +#include <linux/mutex.h> #include <asm/tlbflush.h> #include <asm/io.h> @@ -22,22 +24,18 @@ * 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; 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) { - static DEFINE_SPINLOCK(xip_alloc_lock); - spin_lock(&xip_alloc_lock); - if (!__xip_sparse_page) - __xip_sparse_page = page; - else - __free_page(page); - spin_unlock(&xip_alloc_lock); - } + if (page) + __xip_sparse_page = page; } return __xip_sparse_page; } @@ -174,18 +172,23 @@ __xip_unmap (struct address_space * mapping, pte_t pteval; spinlock_t *ptl; struct page *page; + unsigned count; + int locked = 0; + + count = read_seqcount_begin(&xip_sparse_seq); page = __xip_sparse_page; if (!page) return; +retry: spin_lock(&mapping->i_mmap_lock); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { mm = vma->vm_mm; 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); + pte = page_check_address(page, mm, address, &ptl, 1); if (pte) { /* Nuke the page table entry. */ flush_cache_page(vma, address, pte_pfn(*pte)); @@ -198,6 +201,14 @@ __xip_unmap (struct address_space * mapping, } } spin_unlock(&mapping->i_mmap_lock); + + 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; + } } /* @@ -218,7 +229,7 @@ static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 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; @@ -237,8 +248,10 @@ static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 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 */ @@ -252,14 +265,34 @@ found: 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; /* not shared and writable, use xip_sparse_page() */ page = xip_sparse_page(); if (!page) - return VM_FAULT_OOM; + goto out; + err = vm_insert_page(vma, (unsigned long)vmf->virtual_address, + page); + if (err == -ENOMEM) + goto out; - page_cache_get(page); - vmf->page = page; - return 0; + ret = VM_FAULT_NOPAGE; +out: + write_seqcount_end(&xip_sparse_seq); + mutex_unlock(&xip_sparse_mutex); + + return ret; } } @@ -308,8 +341,10 @@ __xip_file_write(struct file *filp, const char __user *buf, &xip_mem, &xip_pfn); if (status == -ENODATA) { /* we allocate a new page unmap it */ + mutex_lock(&xip_sparse_mutex); status = a_ops->get_xip_mem(mapping, index, 1, &xip_mem, &xip_pfn); + mutex_unlock(&xip_sparse_mutex); if (!status) /* unmap page at pgoff from all other vmas */ __xip_unmap(mapping, index); |