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loop: fold loop_switch() into callers 

The comments here are really outdated, and blk-mq made flushing much
simpler, so just fold the two cases into the callers.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Omar Sandoval 2017-08-24 00:03:44 -07:00 committed by Jens Axboe
parent 89e4fdecb5
commit 43cade803e
1 changed files with 11 additions and 65 deletions
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76
drivers/block/loop.c
View File

@ -546,72 +546,12 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
} }
} }
struct switch_request {
struct file *file;
struct completion wait;
};
static inline void loop_update_dio(struct loop_device *lo) static inline void loop_update_dio(struct loop_device *lo)
{ {
__loop_update_dio(lo, io_is_direct(lo->lo_backing_file) | __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) |
lo->use_dio); lo->use_dio);
} }
/*
* Do the actual switch; called from the BIO completion routine
*/
static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
{
struct file *file = p->file;
struct file *old_file = lo->lo_backing_file;
struct address_space *mapping;
/* if no new file, only flush of queued bios requested */
if (!file)
return;
mapping = file->f_mapping;
mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
lo->lo_backing_file = file;
lo->old_gfp_mask = mapping_gfp_mask(mapping);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
loop_update_dio(lo);
}
/*
* loop_switch performs the hard work of switching a backing store.
* First it needs to flush existing IO, it does this by sending a magic
* BIO down the pipe. The completion of this BIO does the actual switch.
*/
static int loop_switch(struct loop_device *lo, struct file *file)
{
struct switch_request w;
w.file = file;
/* freeze queue and wait for completion of scheduled requests */
blk_mq_freeze_queue(lo->lo_queue);
/* do the switch action */
do_loop_switch(lo, &w);
/* unfreeze */
blk_mq_unfreeze_queue(lo->lo_queue);
return 0;
}
/*
* Helper to flush the IOs in loop, but keeping loop thread running
*/
static int loop_flush(struct loop_device *lo)
{
/* loop not yet configured, no running thread, nothing to flush */
if (lo->lo_state != Lo_bound)
return 0;
return loop_switch(lo, NULL);
}
static void loop_reread_partitions(struct loop_device *lo, static void loop_reread_partitions(struct loop_device *lo,
struct block_device *bdev) struct block_device *bdev)
{ {
@ -676,9 +616,14 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
goto out_putf; goto out_putf;
/* and ... switch */ /* and ... switch */
error = loop_switch(lo, file); blk_mq_freeze_queue(lo->lo_queue);
if (error) mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
goto out_putf; lo->lo_backing_file = file;
lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
mapping_set_gfp_mask(file->f_mapping,
lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
loop_update_dio(lo);
blk_mq_unfreeze_queue(lo->lo_queue);
fput(old_file); fput(old_file);
if (lo->lo_flags & LO_FLAGS_PARTSCAN) if (lo->lo_flags & LO_FLAGS_PARTSCAN)
@ -1601,12 +1546,13 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
err = loop_clr_fd(lo); err = loop_clr_fd(lo);
if (!err) if (!err)
return; return;
} else { } else if (lo->lo_state == Lo_bound) {
/* /*
* Otherwise keep thread (if running) and config, * Otherwise keep thread (if running) and config,
* but flush possible ongoing bios in thread. * but flush possible ongoing bios in thread.
*/ */
loop_flush(lo); blk_mq_freeze_queue(lo->lo_queue);
blk_mq_unfreeze_queue(lo->lo_queue);
} }
mutex_unlock(&lo->lo_ctl_mutex); mutex_unlock(&lo->lo_ctl_mutex);