The function return values are confusing with the way the function is
named. We expect a true or false return value but it actually returns
0/-errno.  This makes the code very confusing. Changing the return values
to return a bool where if DAX is supported then return true and no DAX
support returns false.

Signed-off-by: Dave Jiang <[email protected]>
---
 drivers/dax/super.c |   18 +++++++++---------
 fs/ext2/super.c     |    5 +++--
 fs/ext4/super.c     |    5 +++--
 fs/xfs/xfs_ioctl.c  |    4 ++--
 fs/xfs/xfs_super.c  |   10 +++++-----
 include/linux/dax.h |   12 ++++++------
 6 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index c4db84f26c0f..ef008e384042 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -80,9 +80,9 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
  * This is a library function for filesystems to check if the block device
  * can be mounted with dax option.
  *
- * Return: negative errno if unsupported, 0 if supported.
+ * Return: true if supported, false if unsupported
  */
-int bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
+bool bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
                       int blocksize)
 {
        struct dax_device *dax_dev;
@@ -95,21 +95,21 @@ int bdev_dax_supported(struct super_block *sb, struct 
block_device *bdev,
        if (blocksize != PAGE_SIZE) {
                pr_debug("VFS (%s): error: unsupported blocksize for dax\n",
                                sb->s_id);
-               return -EINVAL;
+               return false;
        }
 
        err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
        if (err) {
-               pr_debug("VFS (%s): error: unaligned partition for dax\n",
-                               sb->s_id);
-               return err;
+               pr_debug("VFS (%s): error: unaligned partition for dax: %d\n",
+                               sb->s_id, err);
+               return false;
        }
 
        dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
        if (!dax_dev) {
                pr_debug("VFS (%s): error: device does not support dax\n",
                                sb->s_id);
-               return -EOPNOTSUPP;
+               return false;
        }
 
        id = dax_read_lock();
@@ -121,10 +121,10 @@ int bdev_dax_supported(struct super_block *sb, struct 
block_device *bdev,
        if (len < 1) {
                pr_debug("VFS (%s): error: dax access failed (%ld)\n",
                                sb->s_id, len);
-               return len < 0 ? len : -EIO;
+               return false;
        }
 
-       return 0;
+       return true;
 }
 EXPORT_SYMBOL_GPL(bdev_dax_supported);
 #endif
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 655699321c45..636b9c5e1bff 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -958,9 +958,10 @@ static int ext2_fill_super(struct super_block *sb, void 
*data, int silent)
        blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 
        if (sbi->s_mount_opt & EXT2_MOUNT_DAX) {
-               err = sb_dax_supported(sb, blocksize);
-               if (err)
+               if(!sb_dax_supported(sb, blocksize)) {
+                       err = -EIO;
                        goto failed_mount;
+               }
        }
 
        /* If the blocksize doesn't match, re-read the thing.. */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 804a2d6729af..7b7650ac9c53 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3712,9 +3712,10 @@ static int ext4_fill_super(struct super_block *sb, void 
*data, int silent)
                                        " that may contain inline data");
                        goto failed_mount;
                }
-               err = sb_dax_supported(sb, blocksize);
-               if (err)
+               if (!sb_dax_supported(sb, blocksize)) {
+                       err = -EIO;
                        goto failed_mount;
+               }
        }
 
        if (ext4_has_feature_encrypt(sb) && es->s_encryption_level) {
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index f9d3f4314f7c..e440d789ed1b 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1102,8 +1102,8 @@ xfs_ioctl_setattr_dax_invalidate(
        if (fa->fsx_xflags & FS_XFLAG_DAX) {
                if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
                        return -EINVAL;
-               if (bdev_dax_supported(sb, xfs_find_bdev_for_inode(VFS_I(ip)),
-                               sb->s_blocksize) < 0)
+               if (!bdev_dax_supported(sb, xfs_find_bdev_for_inode(VFS_I(ip)),
+                               sb->s_blocksize))
                        return -EINVAL;
        }
 
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 5fd60c1fa9db..39b2295bf646 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1649,18 +1649,18 @@ xfs_fs_fill_super(
                sb->s_flags |= SB_I_VERSION;
 
        if (mp->m_flags & XFS_MOUNT_DAX) {
-               int     error2 = 0;
+               bool rtdev_is_dax, datadev_is_dax;
 
                xfs_warn(mp,
                "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
 
-               error = bdev_dax_supported(sb, mp->m_ddev_targp->bt_bdev,
-                               sb->s_blocksize);
+               datadev_is_dax = bdev_dax_supported(sb,
+                               mp->m_ddev_targp->bt_bdev, sb->s_blocksize);
                if (mp->m_rtdev_targp)
-                       error2 = bdev_dax_supported(sb,
+                       rtdev_is_dax = bdev_dax_supported(sb,
                                        mp->m_rtdev_targp->bt_bdev,
                                        sb->s_blocksize);
-               if (error && error2) {
+               if (!rtdev_is_dax && !datadev_is_dax) {
                        xfs_alert(mp,
                        "DAX unsupported by block device. Turning off DAX.");
                        mp->m_flags &= ~XFS_MOUNT_DAX;
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 1107a980f5c3..ee962705fffb 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -40,9 +40,9 @@ static inline void put_dax(struct dax_device *dax_dev)
 
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
 #if IS_ENABLED(CONFIG_FS_DAX)
-int bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
+bool bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
                       int blocksize);
-static inline int sb_dax_supported(struct super_block *sb, int blocksize)
+static inline bool sb_dax_supported(struct super_block *sb, int blocksize)
 {
        return bdev_dax_supported(sb, sb->s_bdev, blocksize);
 }
@@ -59,16 +59,16 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
 #else
-static inline int bdev_dax_supported(struct super_block *sb,
+static inline bool bdev_dax_supported(struct super_block *sb,
                                     struct block_device *bdev,
                                     int blocksize)
 {
-       return -EOPNOTSUPP;
+       return false;
 }
 
-static inline int sb_dax_supported(struct super_block *sb, int blocksize)
+static inline bool sb_dax_supported(struct super_block *sb, int blocksize)
 {
-       return -EOPNOTSUPP;
+       return false;
 }
 
 static inline struct dax_device *fs_dax_get_by_host(const char *host)

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