Re: [PATCH v6 2/2] block_dev: Rename bd_fsfreeze_mutex

[Waiman Long]

On 09/18/2017 07:47 PM, Christoph Hellwig wrote:
> Don't rename it to a way to long name.  Either add a separate mutex
> for your purpose (unless there is interaction between freezing and
> blktrace, which I doubt), or properly comment the usage.

I would agree with you if the long name causes the expressions hard to
read. In this particular case, it is just the single parameter to the
mutex_lock() and mutex_unlock() functions. There is no confusion and
overly long lines. So I think it is OK. In fact, I got the opposite
advices in the past that some people prefer long descriptive names than
short and cryptic names.

Cheers,
Longman

Re: [PATCH v6 2/2] block_dev: Rename bd_fsfreeze_mutex

[Christoph Hellwig]

Don't rename it to a way to long name.  Either add a separate mutex
for your purpose (unless there is interaction between freezing and
blktrace, which I doubt), or properly comment the usage.

[PATCH v6 2/2] block_dev: Rename bd_fsfreeze_mutex

[Waiman Long]

As the bd_fsfreeze_mutex is used by the blktrace subsystem as well,
it is now renamed to bd_fsfreeze_blktrace_mutex to better reflect
its purpose.

Signed-off-by: Waiman Long 
---
 fs/block_dev.c  | 14 +++---
 fs/gfs2/ops_fstype.c|  6 +++---
 fs/nilfs2/super.c   |  6 +++---
 fs/super.c  |  6 +++---
 include/linux/fs.h  |  5 +++--
 kernel/trace/blktrace.c | 14 +++---
 6 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 93d088f..3dea006 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -504,7 +504,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
struct super_block *sb;
int error = 0;
 
-   mutex_lock(>bd_fsfreeze_mutex);
+   mutex_lock(>bd_fsfreeze_blktrace_mutex);
if (++bdev->bd_fsfreeze_count > 1) {
/*
 * We don't even need to grab a reference - the first call
@@ -514,7 +514,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sb = get_super(bdev);
if (sb)
drop_super(sb);
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
return sb;
}
 
@@ -528,13 +528,13 @@ struct super_block *freeze_bdev(struct block_device *bdev)
if (error) {
deactivate_super(sb);
bdev->bd_fsfreeze_count--;
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
return ERR_PTR(error);
}
deactivate_super(sb);
  out:
sync_blockdev(bdev);
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
return sb;  /* thaw_bdev releases s->s_umount */
 }
 EXPORT_SYMBOL(freeze_bdev);
@@ -550,7 +550,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block 
*sb)
 {
int error = -EINVAL;
 
-   mutex_lock(>bd_fsfreeze_mutex);
+   mutex_lock(>bd_fsfreeze_blktrace_mutex);
if (!bdev->bd_fsfreeze_count)
goto out;
 
@@ -568,7 +568,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block 
*sb)
if (error)
bdev->bd_fsfreeze_count++;
 out:
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
return error;
 }
 EXPORT_SYMBOL(thaw_bdev);
@@ -767,7 +767,7 @@ static void init_once(void *foo)
bdev->bd_bdi = _backing_dev_info;
inode_init_once(>vfs_inode);
/* Initialize mutex for freeze. */
-   mutex_init(>bd_fsfreeze_mutex);
+   mutex_init(>bd_fsfreeze_blktrace_mutex);
 }
 
 static void bdev_evict_inode(struct inode *inode)
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index a3711f5..5664905 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1269,14 +1269,14 @@ static struct dentry *gfs2_mount(struct 
file_system_type *fs_type, int flags,
 * will protect the lockfs code from trying to start a snapshot
 * while we are mounting
 */
-   mutex_lock(>bd_fsfreeze_mutex);
+   mutex_lock(>bd_fsfreeze_blktrace_mutex);
if (bdev->bd_fsfreeze_count > 0) {
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
error = -EBUSY;
goto error_bdev;
}
s = sget(fs_type, test_gfs2_super, set_gfs2_super, flags, bdev);
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
error = PTR_ERR(s);
if (IS_ERR(s))
goto error_bdev;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 4fc018d..931b455 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -1306,15 +1306,15 @@ static int nilfs_test_bdev_super(struct super_block *s, 
void *data)
 * will protect the lockfs code from trying to start a snapshot
 * while we are mounting
 */
-   mutex_lock(>bd_fsfreeze_mutex);
+   mutex_lock(>bd_fsfreeze_blktrace_mutex);
if (sd.bdev->bd_fsfreeze_count > 0) {
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
err = -EBUSY;
goto failed;
}
s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
 sd.bdev);
-   mutex_unlock(>bd_fsfreeze_mutex);
+   mutex_unlock(>bd_fsfreeze_blktrace_mutex);
if (IS_ERR(s)) {
err = PTR_ERR(s);
goto failed;
diff --git a/fs/super.c b/fs/super.c
index 166c4ee..079890f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1083,15 +1083,15 @@ struct dentry *mount_bdev(struct file_system_type 
*fs_type,
 * will protect the lockfs code from trying to start a snapshot
 * while we are mounting
 */
-   mutex_lock(>bd_fsfreeze_mutex);
+