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-rw-r--r--fs/dax.c90
1 files changed, 48 insertions, 42 deletions
diff --git a/fs/dax.c b/fs/dax.c
index bcfb14bfc1e4..43671b68220e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -29,6 +29,11 @@
#include <linux/uio.h>
#include <linux/vmstat.h>
+/*
+ * 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;
@@ -169,8 +174,10 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
else
len = iov_iter_zero(max - pos, iter);
- if (!len)
+ if (!len) {
+ retval = -EFAULT;
break;
+ }
pos += len;
addr += len;
@@ -285,6 +292,7 @@ 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;
@@ -292,6 +300,8 @@ 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
@@ -321,6 +331,8 @@ 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;
}
@@ -382,17 +394,15 @@ 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;
+ goto unlock_page;
}
- } 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;
+ goto unlock_page;
if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
if (vmf->flags & FAULT_FLAG_WRITE) {
@@ -403,9 +413,8 @@ 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;
+ goto unlock_page;
} else {
- i_mmap_unlock_write(mapping);
return dax_load_hole(mapping, page, vmf);
}
}
@@ -417,15 +426,17 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
else
clear_user_highpage(new_page, vaddr);
if (error)
- goto unlock;
+ 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 unlock;
+ goto out;
}
}
return VM_FAULT_LOCKED;
@@ -461,8 +472,6 @@ 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;
@@ -471,14 +480,11 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
return VM_FAULT_SIGBUS | major;
return VM_FAULT_NOPAGE | major;
- unlock:
+ unlock_page:
if (page) {
unlock_page(page);
page_cache_release(page);
- } else {
- i_mmap_unlock_write(mapping);
}
-
goto out;
}
EXPORT_SYMBOL(__dax_fault);
@@ -535,6 +541,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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;
@@ -556,10 +566,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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;
+ i_mmap_lock_read(mapping);
/*
* If the filesystem isn't willing to tell us the length of a hole,
@@ -569,36 +579,14 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
goto fallback;
- sector = bh.b_blocknr << (blkbits - 9);
-
- if (buffer_unwritten(&bh) || buffer_new(&bh)) {
- int i;
-
- 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;
-
- 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;
- }
-
/*
* 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);
+ i_mmap_unlock_read(mapping);
unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
- i_mmap_lock_write(mapping);
+ i_mmap_lock_read(mapping);
}
/*
@@ -635,6 +623,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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) {
@@ -644,15 +633,32 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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));
- i_mmap_unlock_write(mapping);
-
return result;
fallback:
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