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-rw-r--r--fs/dax.c257
1 files changed, 63 insertions, 194 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 7d9df93b3a14..5a282260d27e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -87,50 +87,6 @@ struct page *read_dax_sector(struct block_device *bdev, sector_t n)
return page;
}
-/*
- * dax_clear_sectors() 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_sectors(struct block_device *bdev, sector_t _sector, long _size)
-{
- struct blk_dax_ctl dax = {
- .sector = _sector,
- .size = _size,
- };
-
- might_sleep();
- do {
- long count, sz;
-
- count = dax_map_atomic(bdev, &dax);
- if (count < 0)
- return count;
- sz = min_t(long, count, SZ_128K);
- clear_pmem(dax.addr, sz);
- dax.size -= sz;
- dax.sector += sz / 512;
- dax_unmap_atomic(bdev, &dax);
- cond_resched();
- } while (dax.size);
-
- wmb_pmem();
- return 0;
-}
-EXPORT_SYMBOL_GPL(dax_clear_sectors);
-
-/* 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)
- clear_pmem(addr, first);
- if (final < size)
- clear_pmem(addr + final, size - final);
-}
-
static bool buffer_written(struct buffer_head *bh)
{
return buffer_mapped(bh) && !buffer_unwritten(bh);
@@ -169,6 +125,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
struct blk_dax_ctl dax = {
.addr = (void __pmem *) ERR_PTR(-EIO),
};
+ unsigned blkbits = inode->i_blkbits;
+ sector_t file_blks = (i_size_read(inode) + (1 << blkbits) - 1)
+ >> blkbits;
if (rw == READ)
end = min(end, i_size_read(inode));
@@ -176,7 +135,6 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
while (pos < end) {
size_t len;
if (pos == max) {
- unsigned blkbits = inode->i_blkbits;
long page = pos >> PAGE_SHIFT;
sector_t block = page << (PAGE_SHIFT - blkbits);
unsigned first = pos - (block << blkbits);
@@ -192,6 +150,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
bh->b_size = 1 << blkbits;
bh_max = pos - first + bh->b_size;
bdev = bh->b_bdev;
+ /*
+ * We allow uninitialized buffers for writes
+ * beyond EOF as those cannot race with faults
+ */
+ WARN_ON_ONCE(
+ (buffer_new(bh) && block < file_blks) ||
+ (rw == WRITE && buffer_unwritten(bh)));
} else {
unsigned done = bh->b_size -
(bh_max - (pos - first));
@@ -211,11 +176,6 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
rc = map_len;
break;
}
- if (buffer_unwritten(bh) || buffer_new(bh)) {
- dax_new_buf(dax.addr, map_len, first,
- pos, end);
- need_wmb = true;
- }
dax.addr += first;
size = map_len - first;
}
@@ -276,15 +236,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
memset(&bh, 0, sizeof(bh));
bh.b_bdev = inode->i_sb->s_bdev;
- if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) {
- struct address_space *mapping = inode->i_mapping;
+ if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ)
inode_lock(inode);
- retval = filemap_write_and_wait_range(mapping, pos, end - 1);
- if (retval) {
- inode_unlock(inode);
- goto out;
- }
- }
/* Protects against truncate */
if (!(flags & DIO_SKIP_DIO_COUNT))
@@ -305,7 +258,6 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
if (!(flags & DIO_SKIP_DIO_COUNT))
inode_dio_end(inode);
- out:
return retval;
}
EXPORT_SYMBOL_GPL(dax_do_io);
@@ -321,20 +273,11 @@ EXPORT_SYMBOL_GPL(dax_do_io);
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);
- put_page(page);
- return VM_FAULT_SIGBUS;
- }
vmf->page = page;
return VM_FAULT_LOCKED;
@@ -565,33 +508,14 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
.sector = to_sector(bh, inode),
.size = bh->b_size,
};
- 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;
- }
-
if (dax_map_atomic(bdev, &dax) < 0) {
error = PTR_ERR(dax.addr);
goto out;
}
-
- if (buffer_unwritten(bh) || buffer_new(bh)) {
- clear_pmem(dax.addr, PAGE_SIZE);
- wmb_pmem();
- }
dax_unmap_atomic(bdev, &dax);
error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false,
@@ -612,19 +536,13 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
* @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)
+ get_block_t get_block)
{
struct file *file = vma->vm_file;
struct address_space *mapping = file->f_mapping;
@@ -659,15 +577,6 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
put_page(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);
@@ -700,17 +609,8 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
if (error)
goto unlock_page;
vmf->page = page;
- if (!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;
}
@@ -727,23 +627,9 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
page = NULL;
}
- /*
- * 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.
- */
+ /* Filesystem should not return unwritten buffers to us! */
+ WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
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)
@@ -772,7 +658,7 @@ EXPORT_SYMBOL(__dax_fault);
* fault handler for DAX files.
*/
int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
- get_block_t get_block, dax_iodone_t complete_unwritten)
+ get_block_t get_block)
{
int result;
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
@@ -781,7 +667,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
}
- result = __dax_fault(vma, vmf, get_block, complete_unwritten);
+ result = __dax_fault(vma, vmf, get_block);
if (vmf->flags & FAULT_FLAG_WRITE)
sb_end_pagefault(sb);
@@ -815,8 +701,7 @@ static void __dax_dbg(struct buffer_head *bh, unsigned long address,
#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd")
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)
+ pmd_t *pmd, unsigned int flags, get_block_t get_block)
{
struct file *file = vma->vm_file;
struct address_space *mapping = file->f_mapping;
@@ -875,6 +760,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
if (get_block(inode, block, &bh, 1) != 0)
return VM_FAULT_SIGBUS;
alloc = true;
+ WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
}
bdev = bh.b_bdev;
@@ -902,23 +788,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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) {
- dax_pmd_dbg(&bh, address,
- "offset + huge page size > file size");
- goto fallback;
- }
-
if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
spinlock_t *ptl;
pmd_t entry;
@@ -954,8 +823,8 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
long length = dax_map_atomic(bdev, &dax);
if (length < 0) {
- result = VM_FAULT_SIGBUS;
- goto out;
+ dax_pmd_dbg(&bh, address, "dax-error fallback");
+ goto fallback;
}
if (length < PMD_SIZE) {
dax_pmd_dbg(&bh, address, "dax-length too small");
@@ -973,14 +842,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
dax_pmd_dbg(&bh, address, "pfn not in memmap");
goto fallback;
}
-
- if (buffer_unwritten(&bh) || buffer_new(&bh)) {
- clear_pmem(dax.addr, PMD_SIZE);
- wmb_pmem();
- count_vm_event(PGMAJFAULT);
- mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
- result |= VM_FAULT_MAJOR;
- }
dax_unmap_atomic(bdev, &dax);
/*
@@ -1020,9 +881,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
out:
i_mmap_unlock_read(mapping);
- if (buffer_unwritten(&bh))
- complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
-
return result;
fallback:
@@ -1042,8 +900,7 @@ EXPORT_SYMBOL_GPL(__dax_pmd_fault);
* 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)
+ pmd_t *pmd, unsigned int flags, get_block_t get_block)
{
int result;
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
@@ -1052,8 +909,7 @@ int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
}
- result = __dax_pmd_fault(vma, address, pmd, flags, get_block,
- complete_unwritten);
+ result = __dax_pmd_fault(vma, address, pmd, flags, get_block);
if (flags & FAULT_FLAG_WRITE)
sb_end_pagefault(sb);
@@ -1091,6 +947,43 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
}
EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
+static bool dax_range_is_aligned(struct block_device *bdev,
+ unsigned int offset, unsigned int length)
+{
+ unsigned short sector_size = bdev_logical_block_size(bdev);
+
+ if (!IS_ALIGNED(offset, sector_size))
+ return false;
+ if (!IS_ALIGNED(length, sector_size))
+ return false;
+
+ return true;
+}
+
+int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
+ unsigned int offset, unsigned int length)
+{
+ struct blk_dax_ctl dax = {
+ .sector = sector,
+ .size = PAGE_SIZE,
+ };
+
+ if (dax_range_is_aligned(bdev, offset, length)) {
+ sector_t start_sector = dax.sector + (offset >> 9);
+
+ return blkdev_issue_zeroout(bdev, start_sector,
+ length >> 9, GFP_NOFS, true);
+ } else {
+ if (dax_map_atomic(bdev, &dax) < 0)
+ return PTR_ERR(dax.addr);
+ clear_pmem(dax.addr + offset, length);
+ wmb_pmem();
+ dax_unmap_atomic(bdev, &dax);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__dax_zero_page_range);
+
/**
* dax_zero_page_range - zero a range within a page of a DAX file
* @inode: The file being truncated
@@ -1102,12 +995,6 @@ EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
* page in a DAX file. This is intended for hole-punch operations. If
* you are truncating a file, the helper function dax_truncate_page() may be
* more convenient.
- *
- * We work in terms of PAGE_SIZE here for commonality with
- * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
- * took care of disposing of the unnecessary blocks. Even if the filesystem
- * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
- * since the file might be mmapped.
*/
int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
get_block_t get_block)
@@ -1126,23 +1013,11 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
bh.b_bdev = inode->i_sb->s_bdev;
bh.b_size = PAGE_SIZE;
err = get_block(inode, index, &bh, 0);
- if (err < 0)
+ if (err < 0 || !buffer_written(&bh))
return err;
- if (buffer_written(&bh)) {
- struct block_device *bdev = bh.b_bdev;
- struct blk_dax_ctl dax = {
- .sector = to_sector(&bh, inode),
- .size = PAGE_SIZE,
- };
-
- if (dax_map_atomic(bdev, &dax) < 0)
- return PTR_ERR(dax.addr);
- clear_pmem(dax.addr + offset, length);
- wmb_pmem();
- dax_unmap_atomic(bdev, &dax);
- }
- return 0;
+ return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode),
+ offset, length);
}
EXPORT_SYMBOL_GPL(dax_zero_page_range);
@@ -1154,12 +1029,6 @@ EXPORT_SYMBOL_GPL(dax_zero_page_range);
*
* Similar to block_truncate_page(), this function can be called by a
* filesystem when it is truncating a DAX file to handle the partial page.
- *
- * We work in terms of PAGE_SIZE here for commonality with
- * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
- * took care of disposing of the unnecessary blocks. Even if the filesystem
- * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
- * since the file might be mmapped.
*/
int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
{