2018-02-15 17:42:38

by Dave Jiang

[permalink] [raw]
Subject: [PATCH v4 2/3] dax: change bdev_dax_supported() to support boolean returns

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 | 20 ++++++++++----------
fs/ext2/super.c | 3 +--
fs/ext4/super.c | 3 +--
fs/xfs/xfs_ioctl.c | 4 ++--
fs/xfs/xfs_super.c | 10 +++++-----
include/linux/dax.h | 12 ++++++------
6 files changed, 25 insertions(+), 27 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 8a3a168a267f..42e58eea305e 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -81,9 +81,9 @@ 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;
@@ -96,21 +96,21 @@ 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();
@@ -122,7 +122,7 @@ 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;
}

if ((IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn))
@@ -131,10 +131,10 @@ int bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
else {
pr_debug("VFS (%s): error: dax support not enabled\n",
sb->s_id);
- 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 28ca694e9e92..6901ba1d65d1 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 = sb_dax_supported(sb, blocksize);
- if (err) {
+ if(!sb_dax_supported(sb, 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 a09f832aad35..8b4ee5f5c17b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3714,8 +3714,7 @@ 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 = sb_dax_supported(sb, blocksize);
- if (err) {
+ if (!sb_dax_supported(sb, 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 277355f5c084..a6a0efc35c76 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(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 f6c74ef9722c..80658e0f01c2 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1657,18 +1657,18 @@ 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 e640c8a19ec0..f733edd3a9dc 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)


2018-02-18 08:23:39

by kernel test robot

[permalink] [raw]
Subject: Re: [PATCH v4 2/3] dax: change bdev_dax_supported() to support boolean returns

Hi Dave,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v4.16-rc1 next-20180216]
[cannot apply to dgc-xfs/for-next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Dave-Jiang/minimal-DAX-support-for-XFS-realtime-device/20180218-154220
config: i386-randconfig-x003-201807 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

fs//xfs/xfs_super.c: In function 'xfs_fs_fill_super':
>> fs//xfs/xfs_super.c:1660:8: warning: 'rtdev_is_dax' may be used uninitialized in this function [-Wmaybe-uninitialized]
bool rtdev_is_dax, datadev_is_dax;
^~~~~~~~~~~~

vim +/rtdev_is_dax +1660 fs//xfs/xfs_super.c

1566
1567 STATIC int
1568 xfs_fs_fill_super(
1569 struct super_block *sb,
1570 void *data,
1571 int silent)
1572 {
1573 struct inode *root;
1574 struct xfs_mount *mp = NULL;
1575 int flags = 0, error = -ENOMEM;
1576
1577 mp = kzalloc(sizeof(struct xfs_mount), GFP_KERNEL);
1578 if (!mp)
1579 goto out;
1580
1581 spin_lock_init(&mp->m_sb_lock);
1582 mutex_init(&mp->m_growlock);
1583 atomic_set(&mp->m_active_trans, 0);
1584 INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
1585 INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
1586 INIT_DELAYED_WORK(&mp->m_cowblocks_work, xfs_cowblocks_worker);
1587 mp->m_kobj.kobject.kset = xfs_kset;
1588
1589 mp->m_super = sb;
1590 sb->s_fs_info = mp;
1591
1592 error = xfs_parseargs(mp, (char *)data);
1593 if (error)
1594 goto out_free_fsname;
1595
1596 sb_min_blocksize(sb, BBSIZE);
1597 sb->s_xattr = xfs_xattr_handlers;
1598 sb->s_export_op = &xfs_export_operations;
1599 #ifdef CONFIG_XFS_QUOTA
1600 sb->s_qcop = &xfs_quotactl_operations;
1601 sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP | QTYPE_MASK_PRJ;
1602 #endif
1603 sb->s_op = &xfs_super_operations;
1604
1605 if (silent)
1606 flags |= XFS_MFSI_QUIET;
1607
1608 error = xfs_open_devices(mp);
1609 if (error)
1610 goto out_free_fsname;
1611
1612 error = xfs_init_mount_workqueues(mp);
1613 if (error)
1614 goto out_close_devices;
1615
1616 error = xfs_init_percpu_counters(mp);
1617 if (error)
1618 goto out_destroy_workqueues;
1619
1620 /* Allocate stats memory before we do operations that might use it */
1621 mp->m_stats.xs_stats = alloc_percpu(struct xfsstats);
1622 if (!mp->m_stats.xs_stats) {
1623 error = -ENOMEM;
1624 goto out_destroy_counters;
1625 }
1626
1627 error = xfs_readsb(mp, flags);
1628 if (error)
1629 goto out_free_stats;
1630
1631 error = xfs_finish_flags(mp);
1632 if (error)
1633 goto out_free_sb;
1634
1635 error = xfs_setup_devices(mp);
1636 if (error)
1637 goto out_free_sb;
1638
1639 error = xfs_filestream_mount(mp);
1640 if (error)
1641 goto out_free_sb;
1642
1643 /*
1644 * we must configure the block size in the superblock before we run the
1645 * full mount process as the mount process can lookup and cache inodes.
1646 */
1647 sb->s_magic = XFS_SB_MAGIC;
1648 sb->s_blocksize = mp->m_sb.sb_blocksize;
1649 sb->s_blocksize_bits = ffs(sb->s_blocksize) - 1;
1650 sb->s_maxbytes = xfs_max_file_offset(sb->s_blocksize_bits);
1651 sb->s_max_links = XFS_MAXLINK;
1652 sb->s_time_gran = 1;
1653 set_posix_acl_flag(sb);
1654
1655 /* version 5 superblocks support inode version counters. */
1656 if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
1657 sb->s_flags |= SB_I_VERSION;
1658
1659 if (mp->m_flags & XFS_MOUNT_DAX) {
> 1660 bool rtdev_is_dax, datadev_is_dax;
1661
1662 xfs_warn(mp,
1663 "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
1664
1665 datadev_is_dax = bdev_dax_supported(sb,
1666 mp->m_ddev_targp->bt_bdev, sb->s_blocksize);
1667 if (mp->m_rtdev_targp)
1668 rtdev_is_dax = bdev_dax_supported(sb,
1669 mp->m_rtdev_targp->bt_bdev,
1670 sb->s_blocksize);
1671 if (!rtdev_is_dax && !datadev_is_dax) {
1672 xfs_alert(mp,
1673 "DAX unsupported by block device. Turning off DAX.");
1674 mp->m_flags &= ~XFS_MOUNT_DAX;
1675 }
1676 if (xfs_sb_version_hasreflink(&mp->m_sb)) {
1677 xfs_alert(mp,
1678 "DAX and reflink cannot be used together!");
1679 error = -EINVAL;
1680 goto out_filestream_unmount;
1681 }
1682 }
1683
1684 if (mp->m_flags & XFS_MOUNT_DISCARD) {
1685 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1686
1687 if (!blk_queue_discard(q)) {
1688 xfs_warn(mp, "mounting with \"discard\" option, but "
1689 "the device does not support discard");
1690 mp->m_flags &= ~XFS_MOUNT_DISCARD;
1691 }
1692 }
1693
1694 if (xfs_sb_version_hasreflink(&mp->m_sb) && mp->m_sb.sb_rblocks) {
1695 xfs_alert(mp,
1696 "reflink not compatible with realtime device!");
1697 error = -EINVAL;
1698 goto out_filestream_unmount;
1699 }
1700
1701 if (xfs_sb_version_hasrmapbt(&mp->m_sb) && mp->m_sb.sb_rblocks) {
1702 xfs_alert(mp,
1703 "reverse mapping btree not compatible with realtime device!");
1704 error = -EINVAL;
1705 goto out_filestream_unmount;
1706 }
1707
1708 error = xfs_mountfs(mp);
1709 if (error)
1710 goto out_filestream_unmount;
1711
1712 root = igrab(VFS_I(mp->m_rootip));
1713 if (!root) {
1714 error = -ENOENT;
1715 goto out_unmount;
1716 }
1717 sb->s_root = d_make_root(root);
1718 if (!sb->s_root) {
1719 error = -ENOMEM;
1720 goto out_unmount;
1721 }
1722
1723 return 0;
1724
1725 out_filestream_unmount:
1726 xfs_filestream_unmount(mp);
1727 out_free_sb:
1728 xfs_freesb(mp);
1729 out_free_stats:
1730 free_percpu(mp->m_stats.xs_stats);
1731 out_destroy_counters:
1732 xfs_destroy_percpu_counters(mp);
1733 out_destroy_workqueues:
1734 xfs_destroy_mount_workqueues(mp);
1735 out_close_devices:
1736 xfs_close_devices(mp);
1737 out_free_fsname:
1738 xfs_free_fsname(mp);
1739 kfree(mp);
1740 out:
1741 return error;
1742
1743 out_unmount:
1744 xfs_filestream_unmount(mp);
1745 xfs_unmountfs(mp);
1746 goto out_free_sb;
1747 }
1748

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation


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