ext4: skip conversion of uninit extents after direct IO if there isn't any

At the end of direct I/O operation, ext4_ext_direct_IO() always called
ext4_convert_unwritten_extents(), regardless of whether there were any
unwritten extents involved in the I/O or not.

This commit adds a state flag so that ext4_ext_direct_IO() only calls
ext4_convert_unwritten_extents() when necessary.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

3 files changed, 21 insertions, 6 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 00d153f2f261..8825515eeddd 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -322,6 +322,7 @@ static inline __u32 ext4_mask_flags(umode_t mode, __u32 flags)
 #define EXT4_STATE_NO_EXPAND            0x00000008 /* No space for expansion */
 #define EXT4_STATE_DA_ALLOC_CLOSE       0x00000010 /* Alloc DA blks on close */
 #define EXT4_STATE_EXT_MIGRATE          0x00000020 /* Inode is migrating */
+#define EXT4_STATE_DIO_UNWRITTEN        0x00000040 /* need convert on dio done*/
 
 /* Used to pass group descriptor data when online resize is done */
 struct ext4_new_group_input {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 441716f33b4a..e991ae2b461c 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3048,12 +3048,18 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
                 ret = ext4_split_unwritten_extents(handle,
                                                 inode, path, iblock,
                                                 max_blocks, flags);
-                /* flag the io_end struct that we need convert when IO done */
+                /*
+                 * Flag the inode(non aio case) or end_io struct (aio case)
+                 * that this IO needs to convertion to written when IO is
+                 * completed
+                 */
                 if (io)
                         io->flag = DIO_AIO_UNWRITTEN;
+                else
+                        EXT4_I(inode)->i_state |= EXT4_STATE_DIO_UNWRITTEN;
                 goto out;
         }
-        /* DIO end_io complete, convert the filled extent to written */
+        /* async DIO end_io complete, convert the filled extent to written */
         if (flags == EXT4_GET_BLOCKS_DIO_CONVERT_EXT) {
                 ret = ext4_convert_unwritten_extents_dio(handle, inode,
                                                         path);
@@ -3295,10 +3301,16 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
                  * To avoid unecessary convertion for every aio dio rewrite
                  * to the mid of file, here we flag the IO that is really
                  * need the convertion.
-                 *
+                 * For non asycn direct IO case, flag the inode state
+                 * that we need to perform convertion when IO is done.
                  */
-                if (io && flags == EXT4_GET_BLOCKS_DIO_CREATE_EXT)
-                        io->flag = DIO_AIO_UNWRITTEN;
+                if (flags == EXT4_GET_BLOCKS_DIO_CREATE_EXT) {
+                        if (io)
+                                io->flag = DIO_AIO_UNWRITTEN;
+                        else
+                                EXT4_I(inode)->i_state |=
+                                        EXT4_STATE_DIO_UNWRITTEN;;
+                }
         }
         err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
         if (err) {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 12d727f8fedf..a9ed2bce74d1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3772,7 +3772,8 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
                 if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
                         ext4_free_io_end(iocb->private);
                         iocb->private = NULL;
-                } else if (ret > 0) {
+                } else if (ret > 0 && (EXT4_I(inode)->i_state &
+                                       EXT4_STATE_DIO_UNWRITTEN)) {
                         int err;
                         /*
                          * for non AIO case, since the IO is already
@@ -3782,6 +3783,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
                                                              offset, ret);
                         if (err < 0)
                                 ret = err;
+                        EXT4_I(inode)->i_state &= ~EXT4_STATE_DIO_UNWRITTEN;
                 }
                 return ret;
         }