[PATCH v7 12/14] xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL

Dan Williams
2018-03-21T23:07:31Z

In preparation for adding coordination between extent unmap operations
and busy dax-pages, update xfs_break_layouts() to permit it to be called
with the mmap lock held. This lock scheme will be required for
coordinating the break of 'dax layouts' (non-idle dax (ZONE_DEVICE)
pages mapped into the file's address space). Breaking dax layouts will
be added to xfs_break_layouts() in a future patch, for now this preps
the unmap call sites to take and hold XFS_MMAPLOCK_EXCL over the call to
xfs_break_layouts().

Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/xfs/xfs_file.c | 5 +----
fs/xfs/xfs_ioctl.c | 5 +----
fs/xfs/xfs_iops.c | 10 +++++++---
fs/xfs/xfs_pnfs.c | 3 ++-
4 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 9ea08326f876..18edf04811d0 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -768,7 +768,7 @@ xfs_file_fallocate(
struct xfs_inode *ip = XFS_I(inode);
long error;
enum xfs_prealloc_flags flags = 0;
- uint iolock = XFS_IOLOCK_EXCL;
+ uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
loff_t new_size = 0;
bool do_file_insert = false;

@@ -782,9 +782,6 @@ xfs_file_fallocate(
if (error)
goto out_unlock;

- xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
- iolock |= XFS_MMAPLOCK_EXCL;
-
if (mode & FALLOC_FL_PUNCH_HOLE) {
error = xfs_free_file_space(ip, offset, len);
if (error)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 89fb1eb80aae..4151fade4bb1 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -614,7 +614,7 @@ xfs_ioc_space(
struct xfs_inode *ip = XFS_I(inode);
struct iattr iattr;
enum xfs_prealloc_flags flags = 0;
- uint iolock = XFS_IOLOCK_EXCL;
+ uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
int error;

/*
@@ -648,9 +648,6 @@ xfs_ioc_space(
if (error)
goto out_unlock;

- xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
- iolock |= XFS_MMAPLOCK_EXCL;
-
switch (bf->l_whence) {
case 0: /*SEEK_SET*/
break;
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 951e84df5576..d23aa08426f9 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1028,13 +1028,17 @@ xfs_vn_setattr(

if (iattr->ia_valid & ATTR_SIZE) {
struct xfs_inode *ip = XFS_I(d_inode(dentry));
- uint iolock = XFS_IOLOCK_EXCL;
+ uint iolock;
+
+ xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
+ iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;

error = xfs_break_layouts(d_inode(dentry), &iolock);
- if (error)
+ if (error) {
+ xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
return error;
+ }

- xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
error = xfs_vn_setattr_size(dentry, iattr);
xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
} else {
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index aa6c5c193f45..6ea7b0b55d02 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -43,7 +43,8 @@ xfs_break_layouts(
while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
xfs_iunlock(ip, *iolock);
error = break_layout(inode, true);
- *iolock = XFS_IOLOCK_EXCL;
+ *iolock &= ~XFS_IOLOCK_SHARED;
+ *iolock |= XFS_IOLOCK_EXCL;
xfs_ilock(ip, *iolock);
}