On Fri 23-02-18 16:43:27, Dan Williams wrote:
Given that S_DAX is non-zero in the FS_DAX=n + DEV_DAX=y case, another mechanism besides the plain IS_DAX() check to compile out dead filesystem-dax code paths. Without IS_FSDAX() xfs will fail at link time with:
ERROR: "dax_finish_sync_fault" [fs/xfs/xfs.ko] undefined! ERROR: "dax_iomap_fault" [fs/xfs/xfs.ko] undefined! ERROR: "dax_iomap_rw" [fs/xfs/xfs.ko] undefined!This compile failure was previously hidden by the fact that S_DAX was erroneously defined to '0' in the FS_DAX=n + DEV_DAX=y case.
Cc: "Darrick J. Wong" darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org Cc: stable@vger.kernel.org Reported-by: kbuild test robot fengguang.wu@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com
As much as I appreciate that relying on compiler to optimize out dead branches results in nicer looking code this is an example where it backfires. Also having IS_DAX() and IS_FSDAX() doing almost the same, just not exactly the same, is IMHO a recipe for confusion (e.g. a casual reader could think why does ext4 get away with using IS_DAX while XFS has to use IS_FSDAX?). So I'd just prefer to handle this as is usual in other kernel areas - define empty stubs for all exported functions when CONFIG_FS_DAX is not enabled. That way code can stay without ugly ifdefs and we don't have to bother with IS_FSDAX vs IS_DAX distinction in filesystem code. Thoughts?
Honza
fs/xfs/xfs_file.c | 14 +++++++------- fs/xfs/xfs_ioctl.c | 4 ++-- fs/xfs/xfs_iomap.c | 6 +++--- fs/xfs/xfs_reflink.c | 2 +- include/linux/fs.h | 2 ++ 5 files changed, 15 insertions(+), 13 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 9ea08326f876..46a098b90fd0 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -288,7 +288,7 @@ xfs_file_read_iter( if (XFS_FORCED_SHUTDOWN(mp)) return -EIO;
- if (IS_DAX(inode))
- if (IS_FSDAX(inode)) ret = xfs_file_dax_read(iocb, to); else if (iocb->ki_flags & IOCB_DIRECT) ret = xfs_file_dio_aio_read(iocb, to);
@@ -726,7 +726,7 @@ xfs_file_write_iter( if (XFS_FORCED_SHUTDOWN(ip->i_mount)) return -EIO;
- if (IS_DAX(inode))
- if (IS_FSDAX(inode)) ret = xfs_file_dax_write(iocb, from); else if (iocb->ki_flags & IOCB_DIRECT) { /*
@@ -1045,7 +1045,7 @@ __xfs_filemap_fault( } xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
- if (IS_DAX(inode)) {
- if (IS_FSDAX(inode)) { pfn_t pfn;
ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &xfs_iomap_ops); @@ -1070,7 +1070,7 @@ xfs_filemap_fault( { /* DAX can shortcut the normal fault path on write faults! */ return __xfs_filemap_fault(vmf, PE_SIZE_PTE,
IS_DAX(file_inode(vmf->vma->vm_file)) &&
IS_FSDAX(file_inode(vmf->vma->vm_file)) && (vmf->flags & FAULT_FLAG_WRITE));} @@ -1079,7 +1079,7 @@ xfs_filemap_huge_fault( struct vm_fault *vmf, enum page_entry_size pe_size) {
- if (!IS_DAX(file_inode(vmf->vma->vm_file)))
- if (!IS_FSDAX(file_inode(vmf->vma->vm_file))) return VM_FAULT_FALLBACK;
/* DAX can shortcut the normal fault path on write faults! */ @@ -1124,12 +1124,12 @@ xfs_file_mmap( * We don't support synchronous mappings for non-DAX files. At least * until someone comes with a sensible use case. */
- if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
- if (!IS_FSDAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC)) return -EOPNOTSUPP;
file_accessed(filp); vma->vm_ops = &xfs_file_vm_ops;
- if (IS_DAX(file_inode(filp)))
- if (IS_FSDAX(file_inode(filp))) vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE; return 0;
} diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 89fb1eb80aae..234279ff66ce 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1108,9 +1108,9 @@ xfs_ioctl_setattr_dax_invalidate( } /* If the DAX state is not changing, we have nothing to do here. */
- if ((fa->fsx_xflags & FS_XFLAG_DAX) && IS_DAX(inode))
- if ((fa->fsx_xflags & FS_XFLAG_DAX) && IS_FSDAX(inode)) return 0;
- if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode))
- if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_FSDAX(inode)) return 0;
/* lock, flush and invalidate mapping in preparation for flag change */ diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 66e1edbfb2b2..cf794d429aec 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -241,7 +241,7 @@ xfs_iomap_write_direct( * the reserve block pool for bmbt block allocation if there is no space * left but we need to do unwritten extent conversion. */
- if (IS_DAX(VFS_I(ip))) {
- if (IS_FSDAX(VFS_I(ip))) { bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO; if (imap->br_state == XFS_EXT_UNWRITTEN) { tflags |= XFS_TRANS_RESERVE;
@@ -952,7 +952,7 @@ static inline bool imap_needs_alloc(struct inode *inode, return !nimaps || imap->br_startblock == HOLESTARTBLOCK || imap->br_startblock == DELAYSTARTBLOCK ||
(IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);
(IS_FSDAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);} static inline bool need_excl_ilock(struct xfs_inode *ip, unsigned flags) @@ -988,7 +988,7 @@ xfs_file_iomap_begin( return -EIO; if (((flags & (IOMAP_WRITE | IOMAP_DIRECT)) == IOMAP_WRITE) &&
!IS_DAX(inode) && !xfs_get_extsz_hint(ip)) {
!IS_FSDAX(inode) && !xfs_get_extsz_hint(ip)) {diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 270246943a06..a126e00e05e3 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1351,7 +1351,7 @@ xfs_reflink_remap_range( goto out_unlock; /* Don't share DAX file data for now. */
- if (IS_DAX(inode_in) || IS_DAX(inode_out))
- if (IS_FSDAX(inode_in) || IS_FSDAX(inode_out)) goto out_unlock;
ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out, diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..a4310a95011b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1909,6 +1909,8 @@ 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) +#define IS_FSDAX(inode) (IS_ENABLED(CONFIG_FS_DAX) && IS_DAX(inode))
static inline bool HAS_UNMAPPED_ID(struct inode *inode) { return !uid_valid(inode->i_uid) || !gid_valid(inode->i_gid);