The patch titled
Subject: dax: add dax_zero_page_range
has been added to the -mm tree. Its filename is
dax-add-dax_zero_page_range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dax-add-dax_zero_page_range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dax-add-dax_zero_page_range.patch
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------------------------------------------------------
From: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Subject: dax: add dax_zero_page_range
This new function allows us to support hole-punch for DAX files by zeroing
a partial page, as opposed to the dax_truncate_page() function which can
only truncate to the end of the page. Reimplement dax_truncate_page() to
call dax_zero_page_range().
[ross.zwisler@xxxxxxxxxxxxxxx: ported to 3.13-rc2]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Cc: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/dax.txt | 1
fs/dax.c | 36 ++++++++++++++++++++++++----
include/linux/fs.h | 1
3 files changed, 33 insertions(+), 5 deletions(-)
diff -puN Documentation/filesystems/dax.txt~dax-add-dax_zero_page_range Documentation/filesystems/dax.txt
--- a/Documentation/filesystems/dax.txt~dax-add-dax_zero_page_range
+++ a/Documentation/filesystems/dax.txt
@@ -62,6 +62,7 @@ Filesystem support consists of
for fault and page_mkwrite (which should probably call dax_fault() and
dax_mkwrite(), passing the appropriate get_block() callback)
- calling dax_truncate_page() instead of block_truncate_page() for DAX files
+- calling dax_zero_page_range() instead of zero_user() for DAX files
- ensuring that there is sufficient locking between reads, writes,
truncates and page faults
diff -puN fs/dax.c~dax-add-dax_zero_page_range fs/dax.c
--- a/fs/dax.c~dax-add-dax_zero_page_range
+++ a/fs/dax.c
@@ -460,13 +460,16 @@ int dax_fault(struct vm_area_struct *vma
EXPORT_SYMBOL_GPL(dax_fault);
/**
- * dax_truncate_page - handle a partial page being truncated in a DAX file
+ * dax_zero_page_range - zero a range within a page of a DAX file
* @inode: The file being truncated
* @from: The file offset that is being truncated to
+ * @length: The number of bytes to zero
* @get_block: The filesystem method used to translate file offsets to blocks
*
- * Similar to block_truncate_page(), this function can be called by a
- * filesystem when it is truncating an DAX file to handle the partial page.
+ * This function can be called by a filesystem when it is zeroing part of a
+ * 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_CACHE_SIZE here for commonality with
* block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
@@ -474,17 +477,18 @@ EXPORT_SYMBOL_GPL(dax_fault);
* block size is smaller than PAGE_SIZE, we have to zero the rest of the page
* since the file might be mmaped.
*/
-int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
+int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
+ get_block_t get_block)
{
struct buffer_head bh;
pgoff_t index = from >> PAGE_CACHE_SHIFT;
unsigned offset = from & (PAGE_CACHE_SIZE-1);
- unsigned length = PAGE_CACHE_ALIGN(from) - from;
int err;
/* Block boundary? Nothing to do */
if (!length)
return 0;
+ BUG_ON((offset + length) > PAGE_CACHE_SIZE);
memset(&bh, 0, sizeof(bh));
bh.b_size = PAGE_CACHE_SIZE;
@@ -501,4 +505,26 @@ int dax_truncate_page(struct inode *inod
return 0;
}
+EXPORT_SYMBOL_GPL(dax_zero_page_range);
+
+/**
+ * dax_truncate_page - handle a partial page being truncated in a DAX file
+ * @inode: The file being truncated
+ * @from: The file offset that is being truncated to
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ *
+ * Similar to block_truncate_page(), this function can be called by a
+ * filesystem when it is truncating an DAX file to handle the partial page.
+ *
+ * We work in terms of PAGE_CACHE_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 mmaped.
+ */
+int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
+{
+ unsigned length = PAGE_CACHE_ALIGN(from) - from;
+ return dax_zero_page_range(inode, from, length, get_block);
+}
EXPORT_SYMBOL_GPL(dax_truncate_page);
diff -puN include/linux/fs.h~dax-add-dax_zero_page_range include/linux/fs.h
--- a/include/linux/fs.h~dax-add-dax_zero_page_range
+++ a/include/linux/fs.h
@@ -2535,6 +2535,7 @@ extern int nonseekable_open(struct inode
ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, struct iov_iter *,
loff_t, get_block_t, dio_iodone_t, int flags);
int dax_clear_blocks(struct inode *, sector_t block, long size);
+int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
int dax_truncate_page(struct inode *, loff_t from, get_block_t);
int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
#define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb)
_
Patches currently in -mm which might be from matthew.r.wilcox@xxxxxxxxx are
axonram-fix-bug-in-direct_access.patch
block-change-direct_access-calling-convention.patch
mm-fix-xip-fault-vs-truncate-race.patch
mm-fix-xip-fault-vs-truncate-race-fix.patch
mm-allow-page-fault-handlers-to-perform-the-cow.patch
mm-allow-page-fault-handlers-to-perform-the-cow-fix.patch
vfsext2-introduce-is_daxinode.patch
daxext2-replace-xip-read-and-write-with-dax-i-o.patch
daxext2-replace-ext2_clear_xip_target-with-dax_clear_blocks.patch
daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler.patch
daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler-fix.patch
daxext2-replace-xip_truncate_page-with-dax_truncate_page.patch
vfs-remove-get_xip_mem.patch
ext2-remove-ext2_xip_verify_sb.patch
ext2-remove-ext2_use_xip.patch
ext2-remove-xipc-and-xiph.patch
vfsext2-remove-config_ext2_fs_xip-and-rename-config_fs_xip-to-config_fs_dax.patch
ext2-remove-ext2_aops_xip.patch
ext2-get-rid-of-most-mentions-of-xip-in-ext2.patch
dax-add-dax_zero_page_range.patch
dax-add-dax_zero_page_range-fix.patch
ext4-add-dax-functionality.patch
brd-rename-xip-to-dax.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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