vfs,ext2: introduce IS_DAX(inode)

Use an inode flag to tag inodes which should avoid using the page cache.
Convert ext2 to use it instead of mapping_is_xip().  Prevent I/Os to files
tagged with the DAX flag from falling back to buffered I/O.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e49f10cc8a73..fb373bb5cf03 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1677,6 +1677,11 @@ struct super_operations {
 #define S_IMA           1024    /* Inode has an associated IMA struct */
 #define S_AUTOMOUNT     2048    /* Automount/referral quasi-directory */
 #define S_NOSEC         4096    /* no suid or xattr security attributes */
+#ifdef CONFIG_FS_XIP
+#define S_DAX           8192    /* Direct Access, avoiding the page cache */
+#else
+#define S_DAX           0       /* Make all the DAX code disappear */
+#endif
 
 /*
  * Note that nosuid etc flags are inode-specific: setting some file-system
@@ -1714,6 +1719,7 @@ struct super_operations {
 #define IS_IMA(inode)           ((inode)->i_flags & S_IMA)
 #define IS_AUTOMOUNT(inode)     ((inode)->i_flags & S_AUTOMOUNT)
 #define IS_NOSEC(inode)         ((inode)->i_flags & S_NOSEC)
+#define IS_DAX(inode)           ((inode)->i_flags & S_DAX)
 
 #define IS_WHITEOUT(inode)      (S_ISCHR(inode->i_mode) && \
                                  (inode)->i_rdev == WHITEOUT_DEV)