Re: [PATCH v4 02/12] dax: introduce IS_DEVDAX() and IS_FSDAX()

The current IS_DAX() helper that checks the S_DAX inode flag is ambiguous, and currently has the broken assumption that the S_DAX flag

is only non-zero in the CONFIG_FS_DAX=y case. In preparation for defining S_DAX to non-zero in the CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case, introduce two explicit helpers to replace IS_DAX(). Cc: "Theodore Ts'o" <tytso(a)mit.edu&gt; Cc: Andreas Dilger <adilger.kernel(a)dilger.ca&gt; Cc: Alexander Viro <viro(a)zeniv.linux.org.uk&gt; Cc: "Darrick J. Wong" <darrick.wong(a)oracle.com&gt; Cc: linux-xfs(a)vger.kernel.org (supporter:XFS FILESYSTEM) Cc: Matthew Wilcox <mawilcox(a)microsoft.com&gt; Cc: Ross Zwisler <ross.zwisler(a)linux.intel.com&gt; Cc: <stable(a)vger.kernel.org&gt; Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Reported-by: Jan Kara <jack(a)suse.cz&gt; Signed-off-by: Dan Williams <dan.j.williams(a)intel.com&gt; --- include/linux/fs.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..bd0c46880572 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1909,6 +1909,28 @@ static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags #define IS_WHITEOUT(inode) (S_ISCHR(inode->i_mode) && \ (inode)->i_rdev == WHITEOUT_DEV) +static inline bool IS_DEVDAX(struct inode *inode) +{ + if (!IS_ENABLED(CONFIG_DEV_DAX)) + return false; + if ((inode->i_flags & S_DAX) == 0) + return false; + if (!S_ISCHR(inode->i_mode)) + return false; + return true; +} + +static inline bool IS_FSDAX(struct inode *inode) +{ + if (!IS_ENABLED(CONFIG_FS_DAX)) + return false; + if ((inode->i_flags & S_DAX) == 0) + return false; + if (S_ISCHR(inode->i_mode)) + return false; + return true; +} + static inline bool HAS_UNMAPPED_ID(struct inode *inode) { return !uid_valid(inode->i_uid) || !gid_valid(inode->i_gid);