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authorDan Williams <dan.j.williams@intel.com>2018-03-20 14:42:38 -0700
committerDan Williams <dan.j.williams@intel.com>2018-05-22 07:19:08 -0700
commit69eb5fa10eb283e9fcae3ce6f8aaf103b8f0c28d (patch)
tree6ce4847f9262431cc501581d1c43358d116f6c5d /fs/xfs/xfs_pnfs.c
parentc63a8eae63d3859c9c7067aa239a4cfd7423a665 (diff)
downloadlinux-69eb5fa10eb283e9fcae3ce6f8aaf103b8f0c28d.tar.bz2
xfs: prepare xfs_break_layouts() for another layout type
When xfs is operating as the back-end of a pNFS block server, it prevents collisions between local and remote operations by requiring a lease to be held for remotely accessed blocks. Local filesystem operations break those leases before writing or mutating the extent map of the file. A similar mechanism is needed to prevent operations on pinned dax mappings, like device-DMA, from colliding with extent unmap operations. BREAK_WRITE and BREAK_UNMAP are introduced as two distinct levels of layout breaking. Layouts are broken in the BREAK_WRITE case to ensure that layout-holders do not collide with local writes. Additionally, layouts are broken in the BREAK_UNMAP case to make sure the layout-holder has a consistent view of the file's extent map. While BREAK_WRITE breaks can be satisfied be recalling FL_LAYOUT leases, BREAK_UNMAP breaks additionally require waiting for busy dax-pages to go idle while holding XFS_MMAPLOCK_EXCL. After this refactoring xfs_break_layouts() becomes the entry point for coordinating both types of breaks. Finally, xfs_break_leased_layouts() becomes just the BREAK_WRITE handler. Note that the unlock tracking is needed in a follow on change. That will coordinate retrying either break handler until both successfully test for a lease break while maintaining the lock state. Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: "Darrick J. Wong" <darrick.wong@oracle.com> Reported-by: Dave Chinner <david@fromorbit.com> Reported-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'fs/xfs/xfs_pnfs.c')
-rw-r--r--fs/xfs/xfs_pnfs.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 6ea7b0b55d02..f44c3599527d 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -31,17 +31,17 @@
* rules in the page fault path we don't bother.
*/
int
-xfs_break_layouts(
+xfs_break_leased_layouts(
struct inode *inode,
- uint *iolock)
+ uint *iolock,
+ bool *did_unlock)
{
struct xfs_inode *ip = XFS_I(inode);
int error;
- ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
-
while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
xfs_iunlock(ip, *iolock);
+ *did_unlock = true;
error = break_layout(inode, true);
*iolock &= ~XFS_IOLOCK_SHARED;
*iolock |= XFS_IOLOCK_EXCL;
@@ -121,8 +121,8 @@ xfs_fs_map_blocks(
* Lock out any other I/O before we flush and invalidate the pagecache,
* and then hand out a layout to the remote system. This is very
* similar to direct I/O, except that the synchronization is much more
- * complicated. See the comment near xfs_break_layouts for a detailed
- * explanation.
+ * complicated. See the comment near xfs_break_leased_layouts
+ * for a detailed explanation.
*/
xfs_ilock(ip, XFS_IOLOCK_EXCL);