From fbbbad4bc2101e452b24e6e65d3d5e11314a0b5f Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Mon, 16 Feb 2015 15:58:53 -0800 Subject: [PATCH] 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 Reviewed-by: Jan Kara Reviewed-by: Mathieu Desnoyers Cc: Andreas Dilger Cc: Boaz Harrosh Cc: Christoph Hellwig Cc: Dave Chinner Cc: Jens Axboe Cc: Kirill A. Shutemov Cc: Randy Dunlap Cc: Ross Zwisler Cc: Theodore Ts'o Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/inode.c | 9 ++++++--- fs/ext2/xip.h | 2 -- include/linux/fs.h | 6 ++++++ mm/filemap.c | 19 ++++++++++++------- 4 files changed, 24 insertions(+), 12 deletions(-) diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index 36d35c3..0cb0448 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -731,7 +731,7 @@ static int ext2_get_blocks(struct inode *inode, goto cleanup; } - if (ext2_use_xip(inode->i_sb)) { + if (IS_DAX(inode)) { /* * we need to clear the block */ @@ -1201,7 +1201,7 @@ static int ext2_setsize(struct inode *inode, loff_t newsize) inode_dio_wait(inode); - if (mapping_is_xip(inode->i_mapping)) + if (IS_DAX(inode)) error = xip_truncate_page(inode->i_mapping, newsize); else if (test_opt(inode->i_sb, NOBH)) error = nobh_truncate_page(inode->i_mapping, @@ -1273,7 +1273,8 @@ void ext2_set_inode_flags(struct inode *inode) { unsigned int flags = EXT2_I(inode)->i_flags; - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); + inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | + S_DIRSYNC | S_DAX); if (flags & EXT2_SYNC_FL) inode->i_flags |= S_SYNC; if (flags & EXT2_APPEND_FL) @@ -1284,6 +1285,8 @@ void ext2_set_inode_flags(struct inode *inode) inode->i_flags |= S_NOATIME; if (flags & EXT2_DIRSYNC_FL) inode->i_flags |= S_DIRSYNC; + if (test_opt(inode->i_sb, XIP)) + inode->i_flags |= S_DAX; } /* Propagate flags from i_flags to EXT2_I(inode)->i_flags */ diff --git a/fs/ext2/xip.h b/fs/ext2/xip.h index 18b34d2..29be737 100644 --- a/fs/ext2/xip.h +++ b/fs/ext2/xip.h @@ -16,9 +16,7 @@ static inline int ext2_use_xip (struct super_block *sb) } int ext2_get_xip_mem(struct address_space *, pgoff_t, int, void **, unsigned long *); -#define mapping_is_xip(map) unlikely(map->a_ops->get_xip_mem) #else -#define mapping_is_xip(map) 0 #define ext2_xip_verify_sb(sb) do { } while (0) #define ext2_use_xip(sb) 0 #define ext2_clear_xip_target(inode, chain) 0 diff --git a/include/linux/fs.h b/include/linux/fs.h index e49f10c..fb373bb 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) diff --git a/mm/filemap.c b/mm/filemap.c index d9f5336..1578c22 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1723,9 +1723,11 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) * we've already read everything we wanted to, or if * there was a short read because we hit EOF, go ahead * and return. Otherwise fallthrough to buffered io for - * the rest of the read. + * the rest of the read. Buffered reads will not work for + * DAX files, so don't bother trying. */ - if (retval < 0 || !iov_iter_count(iter) || *ppos >= size) { + if (retval < 0 || !iov_iter_count(iter) || *ppos >= size || + IS_DAX(inode)) { file_accessed(file); goto out; } @@ -2587,13 +2589,16 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) loff_t endbyte; written = generic_file_direct_write(iocb, from, pos); - if (written < 0 || written == count) - goto out; - /* - * direct-io write to a hole: fall through to buffered I/O - * for completing the rest of the request. + * If the write stopped short of completing, fall back to + * buffered writes. Some filesystems do this for writes to + * holes, for example. For DAX files, a buffered write will + * not succeed (even if it did, DAX does not handle dirty + * page-cache pages correctly). */ + if (written < 0 || written == count || IS_DAX(inode)) + goto out; + pos += written; count -= written; -- 2.7.4