[PATCH v2 0/3] btrfs: fix several sparse warnings

[PATCH v2 0/3] btrfs: fix several sparse warnings

[Omar Sandoval]

This patch series fixes some warnings reported by sparse when building the
btrfs module. It fixes two classes of warnings: address space warnings and lock
context warnings. This didn't uncover any logical errors, but it reduces the
noise when checking the source. There are a few less straightforward sparse
warnings still remaining.

Version 2 replaces an open-coded implementation of kernel_write in write_buf,
doesn't touch unrelated style issues, and add's David's Reviewed-by.

This patch series applies to 3.17-rc7.

Omar Sandoval (3):
  btrfs: replace open-coded kernel_write
  btrfs: fix sparse address space warnings
  btrfs: fix sparse lock context warnings

 fs/btrfs/extent-tree.c      |  1 +
 fs/btrfs/extent_io.c        |  2 +-
 fs/btrfs/free-space-cache.c |  1 +
 fs/btrfs/ioctl.c            |  6 +++---
 fs/btrfs/locking.c          |  1 +
 fs/btrfs/send.c             | 21 ++++++---------------
 6 files changed, 13 insertions(+), 19 deletions(-)

-- 
2.1.1

[PATCH v2 1/3] btrfs: replace open-coded kernel_write

[Omar Sandoval]

write_buf used by btrfs send has what is more or less a reimplementation of
kernel_write. This also gets rid of a sparse address space warning.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
---
 fs/btrfs/send.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 6528aa6..f6b2ec3 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -508,32 +508,23 @@ static struct btrfs_path *alloc_path_for_send(void)
 static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
 {
 	int ret;
-	mm_segment_t old_fs;
 	u32 pos = 0;
 
-	old_fs = get_fs();
-	set_fs(KERNEL_DS);
-
 	while (pos < len) {
-		ret = vfs_write(filp, (char *)buf + pos, len - pos, off);
+		ret = kernel_write(filp, buf + pos, len - pos, *off);
 		/* TODO handle that correctly */
 		/*if (ret == -ERESTARTSYS) {
 			continue;
 		}*/
 		if (ret < 0)
-			goto out;
-		if (ret == 0) {
-			ret = -EIO;
-			goto out;
-		}
+			return ret;
+		if (ret == 0)
+			return -EIO;
 		pos += ret;
+		*off += ret;
 	}
 
-	ret = 0;
-
-out:
-	set_fs(old_fs);
-	return ret;
+	return 0;
 }
 
 static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
-- 
2.1.1

[PATCH v2 2/3] btrfs: fix sparse address space warnings

[Omar Sandoval]

Several casts of ioctl fields from userspace are missing the __user annotation.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8a8e298..0f9a5a1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2176,7 +2176,7 @@ static noinline int btrfs_ioctl_tree_search_v2(struct file *file,
 
 	inode = file_inode(file);
 	ret = search_ioctl(inode, &args.key, &buf_size,
-			   (char *)(&uarg->buf[0]));
+			   (char __user *)(&uarg->buf[0]));
 	if (ret == 0 && copy_to_user(&uarg->key, &args.key, sizeof(args.key)))
 		ret = -EFAULT;
 	else if (ret == -EOVERFLOW &&
@@ -4247,7 +4247,7 @@ static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
 		ipath->fspath->val[i] = rel_ptr;
 	}
 
-	ret = copy_to_user((void *)(unsigned long)ipa->fspath,
+	ret = copy_to_user((void __user *)(unsigned long)ipa->fspath,
 			   (void *)(unsigned long)ipath->fspath, size);
 	if (ret) {
 		ret = -EFAULT;
@@ -4322,7 +4322,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
 	if (ret < 0)
 		goto out;
 
-	ret = copy_to_user((void *)(unsigned long)loi->inodes,
+	ret = copy_to_user((void __user *)(unsigned long)loi->inodes,
 			   (void *)(unsigned long)inodes, size);
 	if (ret)
 		ret = -EFAULT;
-- 
2.1.1

[PATCH v2 3/3] btrfs: fix sparse lock context warnings

[Omar Sandoval]

Fix several sparse warnings that can easily be addressed with context
annotations. These annotations also provide some sort of documentation for the
internal helper functions.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/extent-tree.c      | 1 +
 fs/btrfs/extent_io.c        | 2 +-
 fs/btrfs/free-space-cache.c | 1 +
 fs/btrfs/locking.c          | 1 +
 4 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3efe1c3..281f30f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6387,6 +6387,7 @@ static struct btrfs_block_group_cache *
 btrfs_lock_cluster(struct btrfs_block_group_cache *block_group,
 		   struct btrfs_free_cluster *cluster,
 		   int delalloc)
+__acquires(&cluster->refill_lock)
 {
 	struct btrfs_block_group_cache *used_bg;
 	bool locked = false;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index af0359d..cc6b1fc 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4775,8 +4775,8 @@ static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
 	__free_extent_buffer(eb);
 }
 
-/* Expects to have eb->eb_lock already held */
 static int release_extent_buffer(struct extent_buffer *eb)
+__releases(&eb->refs_lock)
 {
 	WARN_ON(atomic_read(&eb->refs) == 0);
 	if (atomic_dec_and_test(&eb->refs)) {
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 2b0a627..41c6cd5 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1838,6 +1838,7 @@ static struct btrfs_free_space_op free_space_op = {
 
 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
 			      struct btrfs_free_space *info)
+__must_hold(&ctl->tree_lock)
 {
 	struct btrfs_free_space *bitmap_info;
 	struct btrfs_block_group_cache *block_group = NULL;
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 5665d21..47bdc2c 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -222,6 +222,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
  * blocking readers or writers
  */
 void btrfs_tree_lock(struct extent_buffer *eb)
+__acquires(&eb->lock)
 {
 again:
 	wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
-- 
2.1.1

Re: [PATCH v2 1/3] btrfs: replace open-coded kernel_write

[Zach Brown]

On Tue, Sep 30, 2014 at 03:01:40PM -0700, Omar Sandoval wrote:
> write_buf used by btrfs send has what is more or less a reimplementation of
> kernel_write. This also gets rid of a sparse address space warning.

Seems reasonable to me:

Reviewed-by: Zach Brown <zab@zabbo.net>

- z