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Subject[PATCH v2 2/7] dax: change bdev_dax_supported() to support boolean returns
Date
From: Dave Jiang <dave.jiang@intel.com>

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 <dave.jiang@intel.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
drivers/dax/super.c | 16 ++++++++--------
fs/ext2/super.c | 3 +--
fs/ext4/super.c | 3 +--
fs/xfs/xfs_ioctl.c | 4 ++--
fs/xfs/xfs_super.c | 12 ++++++------
include/linux/dax.h | 8 ++++----
6 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 3943feb9a090..1d7bd96511f0 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 block_device *bdev, int blocksize)
+bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
{
struct dax_device *dax_dev;
pgoff_t pgoff;
@@ -95,21 +95,21 @@ int __bdev_dax_supported(struct block_device *bdev, int blocksize)
if (blocksize != PAGE_SIZE) {
pr_debug("%s: error: unsupported blocksize for dax\n",
bdevname(bdev, buf));
- return -EINVAL;
+ return false;
}

err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
if (err) {
pr_debug("%s: error: unaligned partition for dax\n",
bdevname(bdev, buf));
- return err;
+ return false;
}

dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
if (!dax_dev) {
pr_debug("%s: error: device does not support dax\n",
bdevname(bdev, buf));
- return -EOPNOTSUPP;
+ return false;
}

id = dax_read_lock();
@@ -121,7 +121,7 @@ int __bdev_dax_supported(struct block_device *bdev, int blocksize)
if (len < 1) {
pr_debug("%s: error: dax access failed (%ld)\n",
bdevname(bdev, buf), len);
- return len < 0 ? len : -EIO;
+ return false;
}

if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) {
@@ -139,10 +139,10 @@ int __bdev_dax_supported(struct block_device *bdev, int blocksize)
} else {
pr_debug("%s: error: dax support not enabled\n",
bdevname(bdev, buf));
- return -EOPNOTSUPP;
+ 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 9627c3054b5c..c09289a42dc5 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -961,8 +961,7 @@ 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 = bdev_dax_supported(sb->s_bdev, blocksize);
- if (err) {
+ if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
ext2_msg(sb, KERN_ERR,
"DAX unsupported by block device. Turning off DAX.");
sbi->s_mount_opt &= ~EXT2_MOUNT_DAX;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 089170e99895..2e1622907f4a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3732,8 +3732,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
" that may contain inline data");
sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
}
- err = bdev_dax_supported(sb->s_bdev, blocksize);
- if (err) {
+ if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
ext4_msg(sb, KERN_ERR,
"DAX unsupported by block device. Turning off DAX.");
sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 0effd46b965f..2c70a0a4f59f 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1103,8 +1103,8 @@ 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(xfs_find_bdev_for_inode(VFS_I(ip)),
- sb->s_blocksize) < 0)
+ if (!bdev_dax_supported(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 62188c2a4c36..86915dc40eed 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1690,17 +1690,17 @@ xfs_fs_fill_super(
sb->s_flags |= SB_I_VERSION;

if (mp->m_flags & XFS_MOUNT_DAX) {
- int error2 = 0;
+ bool rtdev_is_dax = false, datadev_is_dax;

xfs_warn(mp,
"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");

- error = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
- sb->s_blocksize);
+ datadev_is_dax = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
+ sb->s_blocksize);
if (mp->m_rtdev_targp)
- error2 = bdev_dax_supported(mp->m_rtdev_targp->bt_bdev,
- sb->s_blocksize);
- if (error && error2) {
+ rtdev_is_dax = bdev_dax_supported(
+ mp->m_rtdev_targp->bt_bdev, sb->s_blocksize);
+ 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 2a4f7295c12b..c99692ddd4b5 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -64,8 +64,8 @@ static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
struct writeback_control;
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 block_device *bdev, int blocksize);
-static inline int bdev_dax_supported(struct block_device *bdev, int blocksize)
+bool __bdev_dax_supported(struct block_device *bdev, int blocksize);
+static inline bool bdev_dax_supported(struct block_device *bdev, int blocksize)
{
return __bdev_dax_supported(bdev, blocksize);
}
@@ -84,10 +84,10 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
int dax_writeback_mapping_range(struct address_space *mapping,
struct block_device *bdev, struct writeback_control *wbc);
#else
-static inline int bdev_dax_supported(struct block_device *bdev,
+static inline bool bdev_dax_supported(struct block_device *bdev,
int blocksize)
{
- return -EOPNOTSUPP;
+ return false;
}

static inline struct dax_device *fs_dax_get_by_host(const char *host)
--
2.14.3
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