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authorZheng Liu <wenqing.lz@taobao.com>2012-07-22 20:19:31 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-07-22 20:19:31 -0400
commit4bd809dbbf177ad0c450d702466b1da63e1b4b7e (patch)
tree80493da203ac42a448489bc8e589207b9f735c2b /fs/ext4/inode.c
parent729f52c6be51013c9268e5fc85acbc1091286fdb (diff)
ext4: don't take the i_mutex lock when doing DIO overwrites
Aligned and overwrite direct I/O can be parallelized. In ext4_file_dio_write, we first check whether these conditions are satisfied or not. If so, we take i_data_sem and release i_mutex lock directly. Meanwhile iocb->private is set to indicate that this is a dio overwrite, and it will be handled in ext4_ext_direct_IO. [ Added fix from Dan Carpenter to fix locking bug on the error path. ] CC: Tao Ma <tm@tao.ma> CC: Eric Sandeen <sandeen@redhat.com> CC: Robin Dong <hao.bigrat@gmail.com> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Diffstat (limited to 'fs/ext4/inode.c')
-rw-r--r--fs/ext4/inode.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 76cb3b1ad78..bed574dd4c2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2996,6 +2996,16 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
if (rw == WRITE && final_size <= inode->i_size) {
int overwrite = 0;
+ BUG_ON(iocb->private == NULL);
+
+ /* If we do a overwrite dio, i_mutex locking can be released */
+ overwrite = *((int *)iocb->private);
+
+ if (overwrite) {
+ down_read(&EXT4_I(inode)->i_data_sem);
+ mutex_unlock(&inode->i_mutex);
+ }
+
/*
* We could direct write to holes and fallocate.
*
@@ -3021,8 +3031,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
if (!is_sync_kiocb(iocb)) {
ext4_io_end_t *io_end =
ext4_init_io_end(inode, GFP_NOFS);
- if (!io_end)
- return -ENOMEM;
+ if (!io_end) {
+ ret = -ENOMEM;
+ goto retake_lock;
+ }
io_end->flag |= EXT4_IO_END_DIRECT;
iocb->private = io_end;
/*
@@ -3083,6 +3095,14 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
ret = err;
ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
}
+
+ retake_lock:
+ /* take i_mutex locking again if we do a ovewrite dio */
+ if (overwrite) {
+ up_read(&EXT4_I(inode)->i_data_sem);
+ mutex_lock(&inode->i_mutex);
+ }
+
return ret;
}