aboutsummaryrefslogtreecommitdiffstats
path: root/fs/dax.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c197
1 files changed, 184 insertions, 13 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 57bb70b4af70..e43389c74bbc 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -283,7 +283,6 @@ static int copy_user_bh(struct page *to, struct buffer_head *bh,
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 __pmem *addr;
@@ -291,8 +290,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
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
@@ -322,8 +319,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
error = vm_insert_mixed(vma, vaddr, pfn);
out:
- i_mmap_unlock_read(mapping);
-
return error;
}
@@ -385,15 +380,17 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
* from a read fault and we've raced with a truncate
*/
error = -EIO;
- goto unlock_page;
+ goto unlock;
}
+ } else {
+ i_mmap_lock_write(mapping);
}
error = get_block(inode, block, &bh, 0);
if (!error && (bh.b_size < PAGE_SIZE))
error = -EIO; /* fs corruption? */
if (error)
- goto unlock_page;
+ goto unlock;
if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
if (vmf->flags & FAULT_FLAG_WRITE) {
@@ -404,8 +401,9 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
if (!error && (bh.b_size < PAGE_SIZE))
error = -EIO;
if (error)
- goto unlock_page;
+ goto unlock;
} else {
+ i_mmap_unlock_write(mapping);
return dax_load_hole(mapping, page, vmf);
}
}
@@ -417,17 +415,15 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
else
clear_user_highpage(new_page, vaddr);
if (error)
- goto unlock_page;
+ goto unlock;
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;
+ goto unlock;
}
}
return VM_FAULT_LOCKED;
@@ -463,6 +459,8 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
}
+ if (!page)
+ i_mmap_unlock_write(mapping);
out:
if (error == -ENOMEM)
return VM_FAULT_OOM | major;
@@ -471,11 +469,14 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
return VM_FAULT_SIGBUS | major;
return VM_FAULT_NOPAGE | major;
- unlock_page:
+ unlock:
if (page) {
unlock_page(page);
page_cache_release(page);
+ } else {
+ i_mmap_unlock_write(mapping);
}
+
goto out;
}
EXPORT_SYMBOL(__dax_fault);
@@ -507,6 +508,176 @@ 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 *kaddr;
+ pgoff_t size, pgoff;
+ sector_t block, sector;
+ unsigned long pfn;
+ int result = 0;
+
+ /* 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;
+ i_mmap_lock_write(mapping);
+ length = get_block(inode, block, &bh, write);
+ if (length)
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * 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 (buffer_unwritten(&bh) || buffer_new(&bh)) {
+ int i;
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ clear_page(kaddr + i * PAGE_SIZE);
+ count_vm_event(PGMAJFAULT);
+ mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+ result |= VM_FAULT_MAJOR;
+ }
+
+ /*
+ * If we allocated new storage, make sure no process has any
+ * zero pages covering this hole
+ */
+ if (buffer_new(&bh)) {
+ i_mmap_unlock_write(mapping);
+ unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
+ i_mmap_lock_write(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;
+
+ result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
+ }
+
+ out:
+ if (buffer_unwritten(&bh))
+ complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
+
+ i_mmap_unlock_write(mapping);
+
+ 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

Privacy Policy