ext4: add ext4_get_block_dax()

Orabug: 22913653

DAX wants different semantics from any currently-existing ext4 get_block
callback.  Unlike ext4_get_block_write(), it needs to honour the
'create' flag, and unlike ext4_get_block(), it needs to be able to
return unwritten extents.  So introduce a new ext4_get_block_dax() which
has those semantics.

We could also change ext4_get_block_write() to honour the 'create' flag,
but that might have consequences on other users that I do not currently
understand.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit ed923b5776a2d2e949bd5b20f3956d68f3c826b7)
Signed-off-by: Dan Duval <dan.duval@oracle.com>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 15213a567301d12f2dbb1a8641a20f417c52206d..7a38683ad071d71085fcd5a77239f2476a607652 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2277,6 +2277,8 @@ struct buffer_head *ext4_getblk(handle_t *, struct inode *, ext4_lblk_t, int);
 struct buffer_head *ext4_bread(handle_t *, struct inode *, ext4_lblk_t, int);
 int ext4_get_block_write(struct inode *inode, sector_t iblock,
                         struct buffer_head *bh_result, int create);
+int ext4_get_block_dax(struct inode *inode, sector_t iblock,
+                        struct buffer_head *bh_result, int create);
 int ext4_get_block(struct inode *inode, sector_t iblock,
                                struct buffer_head *bh_result, int create);
 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 63272b95cb4d18ff5054429a9bc80b4f0d121c60..a9f334f590753920db2b8be6ab924ead31e8aa00 100644 (file)
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -207,19 +207,19 @@ static void ext4_end_io_unwritten(struct buffer_head *bh, int uptodate)
 
 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
-       return dax_fault(vma, vmf, ext4_get_block_write, ext4_end_io_unwritten);
+       return dax_fault(vma, vmf, ext4_get_block_dax, ext4_end_io_unwritten);
 }
 
 static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
                                                pmd_t *pmd, unsigned int flags)
 {
-       return dax_pmd_fault(vma, addr, pmd, flags, ext4_get_block_write,
+       return dax_pmd_fault(vma, addr, pmd, flags, ext4_get_block_dax,
                                ext4_end_io_unwritten);
 }
 
 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
-       return dax_mkwrite(vma, vmf, ext4_get_block_write,
+       return dax_mkwrite(vma, vmf, ext4_get_block_dax,
                                ext4_end_io_unwritten);
 }
 

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c073043b1b5fa9cec62f3c8af65d58fd4787d520..bf63dc5f571b3cfb82ae588d950b99cf0129496d 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3061,6 +3061,17 @@ static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
                               EXT4_GET_BLOCKS_NO_LOCK);
 }
 
+int ext4_get_block_dax(struct inode *inode, sector_t iblock,
+                  struct buffer_head *bh_result, int create)
+{
+       int flags = EXT4_GET_BLOCKS_PRE_IO | EXT4_GET_BLOCKS_UNWRIT_EXT;
+       if (create)
+               flags |= EXT4_GET_BLOCKS_CREATE;
+       ext4_debug("ext4_get_block_dax: inode %lu, create flag %d\n",
+                  inode->i_ino, create);
+       return _ext4_get_block(inode, iblock, bh_result, flags);
+}
+
 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
                            ssize_t size, void *private)
 {