| Message ID | 152001757529.22146.17936438768625217740.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On Fri, Mar 02, 2018 at 11:06:36AM -0800, Dan Williams wrote: > The current IS_DAX() helper that checks if a file is in DAX mode serves > two purposes. It is a control flow branch condition for DAX vs > non-DAX paths and it is a mechanism to perform dead code elimination. The > dead code elimination is required in the CONFIG_FS_DAX=n case since > there are symbols in fs/dax.c that will be elided. While the > dead code elimination can be addressed with nop stubs for the fs/dax.c > symbols that does not address the need for a DAX control flow helper > where fs/dax.c symbols are not involved. > > Moreover, the control flow changes, in some cases, need to be cognizant > of whether the DAX file is a typical file or a Device-DAX special file. > Introduce IS_DEVDAX() and IS_FSDAX() to simultaneously address the > file-type control flow and dead-code elimination use cases. IS_DAX() > will be deleted after all sites are converted to use the file-type > specific helper. > > Note, this change is also a pre-requisite for fixing the definition of > the S_DAX inode flag in the CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case. > The flag needs to be defined, non-zero, if either DAX facility is > enabled. > > 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 > 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> > Reviewed-by: Jan Kara <jack@suse.cz> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > --- > Changes since v5: > * add comments to clarify the S_ISCHR() checks (Darrick) Looks ok, Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > > include/linux/fs.h | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 79c413985305..751975b8b29b 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1909,6 +1909,30 @@ 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; > + /* regular files with S_DAX are filesystem-dax instances */ > + 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; > + /* character devices with S_DAX are device-dax instances */ > + 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); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..751975b8b29b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1909,6 +1909,30 @@ 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; + /* regular files with S_DAX are filesystem-dax instances */ + 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; + /* character devices with S_DAX are device-dax instances */ + 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 if a file is in DAX mode serves two purposes. It is a control flow branch condition for DAX vs non-DAX paths and it is a mechanism to perform dead code elimination. The dead code elimination is required in the CONFIG_FS_DAX=n case since there are symbols in fs/dax.c that will be elided. While the dead code elimination can be addressed with nop stubs for the fs/dax.c symbols that does not address the need for a DAX control flow helper where fs/dax.c symbols are not involved. Moreover, the control flow changes, in some cases, need to be cognizant of whether the DAX file is a typical file or a Device-DAX special file. Introduce IS_DEVDAX() and IS_FSDAX() to simultaneously address the file-type control flow and dead-code elimination use cases. IS_DAX() will be deleted after all sites are converted to use the file-type specific helper. Note, this change is also a pre-requisite for fixing the definition of the S_DAX inode flag in the CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case. The flag needs to be defined, non-zero, if either DAX facility is enabled. 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 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> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- Changes since v5: * add comments to clarify the S_ISCHR() checks (Darrick) include/linux/fs.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)