[PATCH 1/3] btrfs: remove always true if branch in find_delalloc_range

[PATCH 1/3] btrfs: remove always true if branch in find_delalloc_range

[Lu Fengqi]

The @found is always false when it comes to the if branch. Besides, the
bool type is more suitable for @found.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/extent_io.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 582b4b1c41e0..b4ee3399be96 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1461,7 +1461,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 	struct rb_node *node;
 	struct extent_state *state;
 	u64 cur_start = *start;
-	u64 found = 0;
+	bool found = false;
 	u64 total_bytes = 0;
 
 	spin_lock(&tree->lock);
@@ -1472,8 +1472,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 	 */
 	node = tree_search(tree, cur_start);
 	if (!node) {
-		if (!found)
-			*end = (u64)-1;
+		*end = (u64)-1;
 		goto out;
 	}
 
@@ -1493,7 +1492,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 			*cached_state = state;
 			refcount_inc(&state->refs);
 		}
-		found++;
+		found = true;
 		*end = state->end;
 		cur_start = state->end + 1;
 		node = rb_next(node);
-- 
2.19.2

[PATCH 2/3] btrfs: cleanup the useless DEFINE_WAIT in cleanup_transaction

[Lu Fengqi]

When it is introduced at commit f094ac32aba3 ("Btrfs: fix NULL pointer
after aborting a transaction"), it's useless.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/transaction.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f92c0a88c4ad..67e84939b758 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1840,7 +1840,6 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
 {
 	struct btrfs_fs_info *fs_info = trans->fs_info;
 	struct btrfs_transaction *cur_trans = trans->transaction;
-	DEFINE_WAIT(wait);
 
 	WARN_ON(refcount_read(&trans->use_count) > 1);
 
-- 
2.19.2

Re: [PATCH 2/3] btrfs: cleanup the useless DEFINE_WAIT in cleanup_transaction

[Nikolay Borisov]

On 28.11.18 г. 5:22 ч., Lu Fengqi wrote:
> When it is introduced at commit f094ac32aba3 ("Btrfs: fix NULL pointer
> after aborting a transaction"), it's useless.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/transaction.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index f92c0a88c4ad..67e84939b758 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -1840,7 +1840,6 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
>  {
>  	struct btrfs_fs_info *fs_info = trans->fs_info;
>  	struct btrfs_transaction *cur_trans = trans->transaction;
> -	DEFINE_WAIT(wait);
>  
>  	WARN_ON(refcount_read(&trans->use_count) > 1);
>  
> 

Re: [PATCH 2/3] btrfs: cleanup the useless DEFINE_WAIT in cleanup_transaction

[Johannes Thumshirn]

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH 2/3] btrfs: cleanup the useless DEFINE_WAIT in cleanup_transaction

[David Sterba]

On Wed, Nov 28, 2018 at 11:22:54AM +0800, Lu Fengqi wrote:
> When it is introduced at commit f094ac32aba3 ("Btrfs: fix NULL pointer
> after aborting a transaction"), it's useless.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>

Added to misc-next, thanks.

[PATCH 3/3] btrfs: remove redundant nowait check for buffered_write

[Lu Fengqi]

The generic_write_checks will check the combination of IOCB_NOWAIT and
!IOCB_DIRECT.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/file.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3835bb8c146d..190db9a685a2 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1889,10 +1889,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	loff_t oldsize;
 	int clean_page = 0;
 
-	if (!(iocb->ki_flags & IOCB_DIRECT) &&
-	    (iocb->ki_flags & IOCB_NOWAIT))
-		return -EOPNOTSUPP;
-
 	if (!inode_trylock(inode)) {
 		if (iocb->ki_flags & IOCB_NOWAIT)
 			return -EAGAIN;
-- 
2.19.2

Re: [PATCH 3/3] btrfs: remove redundant nowait check for buffered_write

[Nikolay Borisov]

On 28.11.18 г. 5:23 ч., Lu Fengqi wrote:
> The generic_write_checks will check the combination of IOCB_NOWAIT and
> !IOCB_DIRECT.

True, however btrfs will return ENOSUPP whereas the generic code returns
EINVAL. I guess this is not a big deal and it's likely generic code is
correct, so:

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
> ---
>  fs/btrfs/file.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index 3835bb8c146d..190db9a685a2 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1889,10 +1889,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
>  	loff_t oldsize;
>  	int clean_page = 0;
>  
> -	if (!(iocb->ki_flags & IOCB_DIRECT) &&
> -	    (iocb->ki_flags & IOCB_NOWAIT))
> -		return -EOPNOTSUPP;
> -
>  	if (!inode_trylock(inode)) {
>  		if (iocb->ki_flags & IOCB_NOWAIT)
>  			return -EAGAIN;
> 

Re: [PATCH 3/3] btrfs: remove redundant nowait check for buffered_write

[David Sterba]

On Wed, Nov 28, 2018 at 09:04:31AM +0200, Nikolay Borisov wrote:
> On 28.11.18 г. 5:23 ч., Lu Fengqi wrote:
> > The generic_write_checks will check the combination of IOCB_NOWAIT and
> > !IOCB_DIRECT.
> 
> True, however btrfs will return ENOSUPP whereas the generic code returns
> EINVAL. I guess this is not a big deal and it's likely generic code is
> correct, so:

I tried to check the git history if there are some clues for that. The
duplicate checks could be a intermediate step before the aio/nowait
feature was complete but somehow not removed at the end.

The btrfs part was Added in commit
91f9943e1c7b6638f27312d03fe71fcc67b23571 "fs: support RWF_NOWAIT for
buffered reads" (4.13)

The generic checks were added in
6be96d3ad34a124450028dabba43f07fe1d0c86d (4.12), so from that it seems
that it was added tot btrfs as redundant already.

Re: [PATCH 3/3] btrfs: remove redundant nowait check for buffered_write

[Johannes Thumshirn]

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH 1/3] btrfs: remove always true if branch in find_delalloc_range

[Nikolay Borisov]

On 28.11.18 г. 5:21 ч., Lu Fengqi wrote:
> The @found is always false when it comes to the if branch. Besides, the
> bool type is more suitable for @found.

Well if you are ranging the type of found variable it also makes sense
to change the return value of the function to bool as well.

> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
> ---
>  fs/btrfs/extent_io.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 582b4b1c41e0..b4ee3399be96 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -1461,7 +1461,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>  	struct rb_node *node;
>  	struct extent_state *state;
>  	u64 cur_start = *start;
> -	u64 found = 0;
> +	bool found = false;
>  	u64 total_bytes = 0;
>  
>  	spin_lock(&tree->lock);
> @@ -1472,8 +1472,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>  	 */
>  	node = tree_search(tree, cur_start);
>  	if (!node) {
> -		if (!found)
> -			*end = (u64)-1;
> +		*end = (u64)-1;
>  		goto out;
>  	}
>  
> @@ -1493,7 +1492,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>  			*cached_state = state;
>  			refcount_inc(&state->refs);
>  		}
> -		found++;
> +		found = true;
>  		*end = state->end;
>  		cur_start = state->end + 1;
>  		node = rb_next(node);
> 

Re: [PATCH 1/3] btrfs: remove always true if branch in find_delalloc_range

[Lu Fengqi]

On Wed, Nov 28, 2018 at 09:01:42AM +0200, Nikolay Borisov wrote:
>
>
>On 28.11.18 г. 5:21 ч., Lu Fengqi wrote:
>> The @found is always false when it comes to the if branch. Besides, the
>> bool type is more suitable for @found.
>
>Well if you are ranging the type of found variable it also makes sense
>to change the return value of the function to bool as well.

Good catch.

-- 
Thanks,
Lu

>
>> 
>> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
>> ---
>>  fs/btrfs/extent_io.c | 7 +++----
>>  1 file changed, 3 insertions(+), 4 deletions(-)
>> 
>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
>> index 582b4b1c41e0..b4ee3399be96 100644
>> --- a/fs/btrfs/extent_io.c
>> +++ b/fs/btrfs/extent_io.c
>> @@ -1461,7 +1461,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>>  	struct rb_node *node;
>>  	struct extent_state *state;
>>  	u64 cur_start = *start;
>> -	u64 found = 0;
>> +	bool found = false;
>>  	u64 total_bytes = 0;
>>  
>>  	spin_lock(&tree->lock);
>> @@ -1472,8 +1472,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>>  	 */
>>  	node = tree_search(tree, cur_start);
>>  	if (!node) {
>> -		if (!found)
>> -			*end = (u64)-1;
>> +		*end = (u64)-1;
>>  		goto out;
>>  	}
>>  
>> @@ -1493,7 +1492,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>>  			*cached_state = state;
>>  			refcount_inc(&state->refs);
>>  		}
>> -		found++;
>> +		found = true;
>>  		*end = state->end;
>>  		cur_start = state->end + 1;
>>  		node = rb_next(node);
>> 
>
>

[PATCH v2 1/3] btrfs: remove always true if branch in find_delalloc_range

[Lu Fengqi]

The @found is always false when it comes to the if branch. Besides, the
bool type is more suitable for @found. Change the return value of the
function and its caller to bool as well.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/extent_io.c             | 31 +++++++++++++++----------------
 fs/btrfs/extent_io.h             |  2 +-
 fs/btrfs/tests/extent-io-tests.c |  2 +-
 3 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index b2769e92b556..4b6b87e63b4a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1452,16 +1452,16 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
  * find a contiguous range of bytes in the file marked as delalloc, not
  * more than 'max_bytes'.  start and end are used to return the range,
  *
- * 1 is returned if we find something, 0 if nothing was in the tree
+ * true is returned if we find something, false if nothing was in the tree
  */
-static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
+static noinline bool find_delalloc_range(struct extent_io_tree *tree,
 					u64 *start, u64 *end, u64 max_bytes,
 					struct extent_state **cached_state)
 {
 	struct rb_node *node;
 	struct extent_state *state;
 	u64 cur_start = *start;
-	u64 found = 0;
+	bool found = false;
 	u64 total_bytes = 0;
 
 	spin_lock(&tree->lock);
@@ -1472,8 +1472,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 	 */
 	node = tree_search(tree, cur_start);
 	if (!node) {
-		if (!found)
-			*end = (u64)-1;
+		*end = (u64)-1;
 		goto out;
 	}
 
@@ -1493,7 +1492,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 			*cached_state = state;
 			refcount_inc(&state->refs);
 		}
-		found++;
+		found = true;
 		*end = state->end;
 		cur_start = state->end + 1;
 		node = rb_next(node);
@@ -1551,13 +1550,13 @@ static noinline int lock_delalloc_pages(struct inode *inode,
 }
 
 /*
- * find a contiguous range of bytes in the file marked as delalloc, not
- * more than 'max_bytes'.  start and end are used to return the range,
+ * find and lock a contiguous range of bytes in the file marked as delalloc,
+ * not more than 'max_bytes'.  start and end are used to return the range,
  *
- * 1 is returned if we find something, 0 if nothing was in the tree
+ * true is returned if we find something, false if nothing was in the tree
  */
 EXPORT_FOR_TESTS
-noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
+noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
 				    struct extent_io_tree *tree,
 				    struct page *locked_page, u64 *start,
 				    u64 *end)
@@ -1565,7 +1564,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
 	u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
 	u64 delalloc_start;
 	u64 delalloc_end;
-	u64 found;
+	bool found;
 	struct extent_state *cached_state = NULL;
 	int ret;
 	int loops = 0;
@@ -1580,7 +1579,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
 		*start = delalloc_start;
 		*end = delalloc_end;
 		free_extent_state(cached_state);
-		return 0;
+		return false;
 	}
 
 	/*
@@ -1612,7 +1611,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
 			loops = 1;
 			goto again;
 		} else {
-			found = 0;
+			found = false;
 			goto out_failed;
 		}
 	}
@@ -3195,7 +3194,7 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode,
 {
 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 	u64 page_end = delalloc_start + PAGE_SIZE - 1;
-	u64 nr_delalloc;
+	bool found;
 	u64 delalloc_to_write = 0;
 	u64 delalloc_end = 0;
 	int ret;
@@ -3203,11 +3202,11 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode,
 
 
 	while (delalloc_end < page_end) {
-		nr_delalloc = find_lock_delalloc_range(inode, tree,
+		found = find_lock_delalloc_range(inode, tree,
 					       page,
 					       &delalloc_start,
 					       &delalloc_end);
-		if (nr_delalloc == 0) {
+		if (!found) {
 			delalloc_start = delalloc_end + 1;
 			continue;
 		}
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index a1d3ea5a0d32..67881bca15fe 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -521,7 +521,7 @@ int free_io_failure(struct extent_io_tree *failure_tree,
 		    struct extent_io_tree *io_tree,
 		    struct io_failure_record *rec);
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-u64 find_lock_delalloc_range(struct inode *inode, struct extent_io_tree *tree,
+bool find_lock_delalloc_range(struct inode *inode, struct extent_io_tree *tree,
 			     struct page *locked_page, u64 *start,
 			     u64 *end);
 #endif
diff --git a/fs/btrfs/tests/extent-io-tests.c b/fs/btrfs/tests/extent-io-tests.c
index d33f9a95bce1..3c46d7f23456 100644
--- a/fs/btrfs/tests/extent-io-tests.c
+++ b/fs/btrfs/tests/extent-io-tests.c
@@ -66,7 +66,7 @@ static int test_find_delalloc(u32 sectorsize)
 	u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
 	u64 total_dirty = 2 * max_bytes;
 	u64 start, end, test_start;
-	u64 found;
+	bool found;
 	int ret = -EINVAL;
 
 	test_msg("running find delalloc tests");
-- 
2.19.2

Re: [PATCH v2 1/3] btrfs: remove always true if branch in find_delalloc_range

[Nikolay Borisov]

On 29.11.18 г. 5:33 ч., Lu Fengqi wrote:
> The @found is always false when it comes to the if branch. Besides, the
> bool type is more suitable for @found. Change the return value of the
> function and its caller to bool as well.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/extent_io.c             | 31 +++++++++++++++----------------
>  fs/btrfs/extent_io.h             |  2 +-
>  fs/btrfs/tests/extent-io-tests.c |  2 +-
>  3 files changed, 17 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index b2769e92b556..4b6b87e63b4a 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -1452,16 +1452,16 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
>   * find a contiguous range of bytes in the file marked as delalloc, not
>   * more than 'max_bytes'.  start and end are used to return the range,
>   *
> - * 1 is returned if we find something, 0 if nothing was in the tree
> + * true is returned if we find something, false if nothing was in the tree
>   */
> -static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
> +static noinline bool find_delalloc_range(struct extent_io_tree *tree,
>  					u64 *start, u64 *end, u64 max_bytes,
>  					struct extent_state **cached_state)
>  {
>  	struct rb_node *node;
>  	struct extent_state *state;
>  	u64 cur_start = *start;
> -	u64 found = 0;
> +	bool found = false;
>  	u64 total_bytes = 0;
>  
>  	spin_lock(&tree->lock);
> @@ -1472,8 +1472,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>  	 */
>  	node = tree_search(tree, cur_start);
>  	if (!node) {
> -		if (!found)
> -			*end = (u64)-1;
> +		*end = (u64)-1;
>  		goto out;
>  	}
>  
> @@ -1493,7 +1492,7 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
>  			*cached_state = state;
>  			refcount_inc(&state->refs);
>  		}
> -		found++;
> +		found = true;
>  		*end = state->end;
>  		cur_start = state->end + 1;
>  		node = rb_next(node);
> @@ -1551,13 +1550,13 @@ static noinline int lock_delalloc_pages(struct inode *inode,
>  }
>  
>  /*
> - * find a contiguous range of bytes in the file marked as delalloc, not
> - * more than 'max_bytes'.  start and end are used to return the range,
> + * find and lock a contiguous range of bytes in the file marked as delalloc,
> + * not more than 'max_bytes'.  start and end are used to return the range,
>   *
> - * 1 is returned if we find something, 0 if nothing was in the tree
> + * true is returned if we find something, false if nothing was in the tree
>   */
>  EXPORT_FOR_TESTS
> -noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
> +noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
>  				    struct extent_io_tree *tree,
>  				    struct page *locked_page, u64 *start,
>  				    u64 *end)
> @@ -1565,7 +1564,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
>  	u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
>  	u64 delalloc_start;
>  	u64 delalloc_end;
> -	u64 found;
> +	bool found;
>  	struct extent_state *cached_state = NULL;
>  	int ret;
>  	int loops = 0;
> @@ -1580,7 +1579,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
>  		*start = delalloc_start;
>  		*end = delalloc_end;
>  		free_extent_state(cached_state);
> -		return 0;
> +		return false;
>  	}
>  
>  	/*
> @@ -1612,7 +1611,7 @@ noinline_for_stack u64 find_lock_delalloc_range(struct inode *inode,
>  			loops = 1;
>  			goto again;
>  		} else {
> -			found = 0;
> +			found = false;
>  			goto out_failed;
>  		}
>  	}
> @@ -3195,7 +3194,7 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode,
>  {
>  	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
>  	u64 page_end = delalloc_start + PAGE_SIZE - 1;
> -	u64 nr_delalloc;
> +	bool found;
>  	u64 delalloc_to_write = 0;
>  	u64 delalloc_end = 0;
>  	int ret;
> @@ -3203,11 +3202,11 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode,
>  
>  
>  	while (delalloc_end < page_end) {
> -		nr_delalloc = find_lock_delalloc_range(inode, tree,
> +		found = find_lock_delalloc_range(inode, tree,
>  					       page,
>  					       &delalloc_start,
>  					       &delalloc_end);
> -		if (nr_delalloc == 0) {
> +		if (!found) {
>  			delalloc_start = delalloc_end + 1;
>  			continue;
>  		}
> diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
> index a1d3ea5a0d32..67881bca15fe 100644
> --- a/fs/btrfs/extent_io.h
> +++ b/fs/btrfs/extent_io.h
> @@ -521,7 +521,7 @@ int free_io_failure(struct extent_io_tree *failure_tree,
>  		    struct extent_io_tree *io_tree,
>  		    struct io_failure_record *rec);
>  #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
> -u64 find_lock_delalloc_range(struct inode *inode, struct extent_io_tree *tree,
> +bool find_lock_delalloc_range(struct inode *inode, struct extent_io_tree *tree,
>  			     struct page *locked_page, u64 *start,
>  			     u64 *end);
>  #endif
> diff --git a/fs/btrfs/tests/extent-io-tests.c b/fs/btrfs/tests/extent-io-tests.c
> index d33f9a95bce1..3c46d7f23456 100644
> --- a/fs/btrfs/tests/extent-io-tests.c
> +++ b/fs/btrfs/tests/extent-io-tests.c
> @@ -66,7 +66,7 @@ static int test_find_delalloc(u32 sectorsize)
>  	u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
>  	u64 total_dirty = 2 * max_bytes;
>  	u64 start, end, test_start;
> -	u64 found;
> +	bool found;
>  	int ret = -EINVAL;
>  
>  	test_msg("running find delalloc tests");
> 

Re: [PATCH v2 1/3] btrfs: remove always true if branch in find_delalloc_range

[David Sterba]

On Thu, Nov 29, 2018 at 11:33:38AM +0800, Lu Fengqi wrote:
> The @found is always false when it comes to the if branch. Besides, the
> bool type is more suitable for @found. Change the return value of the
> function and its caller to bool as well.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>

Added to misc-next, thanks.