summaryrefslogtreecommitdiff
path: root/fs/dax.c
diff options
context:
space:
mode:
authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
commite5fd91f1ef340da553f7a79da9540c3db711c937 (patch)
treeb11842027dc6641da63f4bcc524f8678263304a3 /fs/dax.c
parent2a9b0348e685a63d97486f6749622b61e9e3292f (diff)
Linux-libre 4.2-gnu
Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c52
1 files changed, 42 insertions, 10 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 6f65f00e5..a7f77e1fa 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -155,7 +155,7 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
}
if (iov_iter_rw(iter) == WRITE)
- len = copy_from_iter(addr, max - pos, iter);
+ len = copy_from_iter_nocache(addr, max - pos, iter);
else if (!hole)
len = copy_to_iter(addr, max - pos, iter);
else
@@ -209,7 +209,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
}
/* Protects against truncate */
- inode_dio_begin(inode);
+ if (!(flags & DIO_SKIP_DIO_COUNT))
+ inode_dio_begin(inode);
retval = dax_io(inode, iter, pos, end, get_block, &bh);
@@ -219,7 +220,8 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
if ((retval > 0) && end_io)
end_io(iocb, pos, retval, bh.b_private);
- inode_dio_end(inode);
+ if (!(flags & DIO_SKIP_DIO_COUNT))
+ inode_dio_end(inode);
out:
return retval;
}
@@ -309,14 +311,27 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
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)
+/**
+ * __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
+ * @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)
{
struct file *file = vma->vm_file;
struct address_space *mapping = file->f_mapping;
@@ -417,7 +432,23 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
page_cache_release(page);
}
+ /*
+ * 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.
+ */
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)
@@ -434,6 +465,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}
goto out;
}
+EXPORT_SYMBOL(__dax_fault);
/**
* dax_fault - handle a page fault on a DAX file
@@ -445,7 +477,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
* fault handler for DAX files.
*/
int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
- get_block_t get_block)
+ get_block_t get_block, dax_iodone_t complete_unwritten)
{
int result;
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
@@ -454,7 +486,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
}
- result = do_dax_fault(vma, vmf, get_block);
+ result = __dax_fault(vma, vmf, get_block, complete_unwritten);
if (vmf->flags & FAULT_FLAG_WRITE)
sb_end_pagefault(sb);