fs: only inc/dec inode->i_dio_count for file systems

We don't need truncate protection for block devices, so add a flag
bypassing this cache line dirtying for every IO.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index ab3a456f66506a5a134f5280739e82c572b15f55..c854484b23a8cfb94e386000eec46027a472beba 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -164,7 +164,8 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
        struct inode *inode = file->f_mapping->host;
 
        return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
-                                   nr_segs, blkdev_get_block, NULL, NULL, 0);
+                                   nr_segs, blkdev_get_block, NULL, NULL,
+                                   DIO_IGNORE_TRUNCATE);
 }
 
 int __sync_blockdev(struct block_device *bdev, int wait)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 556ad359a2ef8f9984b51827eaea2a02cdb29213..d5594da84e5d125eb52fed4b115f67b2287f9e97 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -268,7 +268,10 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
        } else {
                if (is_async)
                        aio_complete(dio->iocb, ret, 0);
-               inode_dio_done(dio->inode);
+               if (dio->flags & DIO_IGNORE_TRUNCATE)
+                       __inode_dio_done(dio->inode);
+               else
+                       inode_dio_done(dio->inode);
        }
 
        return ret;
@@ -1125,9 +1128,12 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
        }
 
        /*
-        * Will be decremented at I/O completion time.
+        * Will be decremented at I/O completion time. For a block device
+        * we don't need to protect against truncate, so don't increment
+        * the inode direct IO count.
         */
-       atomic_inc(&inode->i_dio_count);
+       if (!(dio->flags & DIO_IGNORE_TRUNCATE))
+               atomic_inc(&inode->i_dio_count);
 
        /*
         * For file extending writes updating i_size before data

diff --git a/fs/inode.c b/fs/inode.c
index 64999f144153d7740018203f884c24eb2a829f54..dd5fc965b11f8c98ecb414419b009a94959c0946 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1888,6 +1888,11 @@ void inode_dio_wait(struct inode *inode)
 }
 EXPORT_SYMBOL(inode_dio_wait);
 
+void __inode_dio_done(struct inode *inode)
+{
+       wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
+}
+
 /*
  * inode_dio_done - signal finish of a direct I/O requests
  * @inode: inode the direct I/O happens on
@@ -1898,6 +1903,6 @@ EXPORT_SYMBOL(inode_dio_wait);
 void inode_dio_done(struct inode *inode)
 {
        if (atomic_dec_and_test(&inode->i_dio_count))
-               wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
+               __inode_dio_done(inode);
 }
 EXPORT_SYMBOL(inode_dio_done);

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 75fe9a1348036c52b863fb47737eb6b0f9dd8789..4da47e5c00095f01dc15761d101a9af63f9a66da 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2428,6 +2428,9 @@ enum {
 
        /* filesystem does not support filling holes */
        DIO_SKIP_HOLES  = 0x02,
+
+       /* inode/fs/bdev does not need truncate protection */
+       DIO_IGNORE_TRUNCATE = 0x04,
 };
 
 void dio_end_io(struct bio *bio, int error);
@@ -2448,6 +2451,7 @@ static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
 #endif
 
 void inode_dio_wait(struct inode *inode);
+void __inode_dio_done(struct inode *inode);
 void inode_dio_done(struct inode *inode);
 
 extern const struct file_operations generic_ro_fops;