| Message ID | 151970520551.26729.12707678649514382892.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon 26-02-18 20:20:05, Dan Williams wrote: > 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 I don't think S_DAX flag is really ambiguous. It is just that in CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case, the compiler is not able to figure out some calls behind IS_DAX() are dead code and so the kernel won't compile / link. Or is there any other problem I'm missing? If I'm indeed right, then please tell this in the changelog and don't talk about abstract ambiguity of S_DAX flag. As much as I'd prefer to solve link-time problems with stubs instead of relying on dead-code elimination, I can live with split macros so once the changelog is settled, feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > 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@mit.edu> > Cc: Andreas Dilger <adilger.kernel@dilger.ca> > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: "Darrick J. Wong" <darrick.wong@oracle.com> > Cc: linux-xfs@vger.kernel.org (supporter:XFS FILESYSTEM) > Cc: Matthew Wilcox <mawilcox@microsoft.com> > Cc: Ross Zwisler <ross.zwisler@linux.intel.com> > Cc: <stable@vger.kernel.org> > Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") > Reported-by: Jan Kara <jack@suse.cz> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > --- > 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); >
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);
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@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Darrick J. Wong" <darrick.wong@oracle.com> Cc: linux-xfs@vger.kernel.org (supporter:XFS FILESYSTEM) Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: <stable@vger.kernel.org> Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- include/linux/fs.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)