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Subject[PATCH v5 10/11] xfs: prepare xfs_break_layouts() for another layout type
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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.

XFS_BREAK_REMOTE and XFS_BREAK_MAPS are introduced as flags to control
the layouts that need to be broken by xfs_break_layouts(). While
XFS_BREAK_REMOTE is invoked in all calls to the new xfs_break_layouts(),
XFS_BREAK_MAPS only needs to specified when extents may be unmapped,
i.e. xfs_file_fallocate() and xfs_ioc_space(). XFS_BREAK_MAPS also
imposes the additional locking constraint of breaking (awaiting) pinned
dax mappings while holding XFS_MMAPLOCK_EXCL.

There is a small functional change in this rework. For the cases where
XFS_BREAK_MAPS is specified to xfs_break_layouts(), the
XFS_MMAPLOCK_EXCL ilock is held over the break_layouts() loop in
xfs_break_leased_layouts().

Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/xfs/xfs_file.c | 32 ++++++++++++++++++++++++++------
fs/xfs/xfs_inode.h | 9 +++++++++
fs/xfs/xfs_ioctl.c | 9 +++------
fs/xfs/xfs_iops.c | 12 +++++++-----
fs/xfs/xfs_pnfs.c | 8 +++-----
fs/xfs/xfs_pnfs.h | 4 ++--
6 files changed, 50 insertions(+), 24 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 9ea08326f876..f914f0628dc2 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -350,7 +350,7 @@ xfs_file_aio_write_checks(
if (error <= 0)
return error;

- error = xfs_break_layouts(inode, iolock);
+ error = xfs_break_layouts(inode, iolock, XFS_BREAK_REMOTE);
if (error)
return error;

@@ -752,6 +752,28 @@ xfs_file_write_iter(
return ret;
}

+int
+xfs_break_layouts(
+ struct inode *inode,
+ uint *iolock,
+ unsigned long flags)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ uint iolock_assert = 0;
+ int ret = 0;
+
+ if (flags & XFS_BREAK_REMOTE)
+ iolock_assert |= XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL;
+ if (flags & XFS_BREAK_MAPS)
+ iolock_assert |= XFS_MMAPLOCK_EXCL;
+
+ ASSERT(xfs_isilocked(ip, iolock_assert));
+
+ if (flags & XFS_BREAK_REMOTE)
+ ret = xfs_break_leased_layouts(inode, iolock);
+ return ret;
+}
+
#define XFS_FALLOC_FL_SUPPORTED \
(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | \
@@ -768,7 +790,7 @@ 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;

@@ -778,13 +800,11 @@ xfs_file_fallocate(
return -EOPNOTSUPP;

xfs_ilock(ip, iolock);
- error = xfs_break_layouts(inode, &iolock);
+ error = xfs_break_layouts(inode, &iolock,
+ XFS_BREAK_REMOTE | XFS_BREAK_MAPS);
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_inode.h b/fs/xfs/xfs_inode.h
index 3e8dc990d41c..9b73ceb09cb1 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -379,6 +379,12 @@ static inline void xfs_ifunlock(struct xfs_inode *ip)
>> XFS_ILOCK_SHIFT)

/*
+ * Flags for layout breaks
+ */
+#define XFS_BREAK_REMOTE (1<<0) /* break remote layout leases */
+#define XFS_BREAK_MAPS (1<<1) /* break local direct (dax) mappings */
+
+/*
* For multiple groups support: if S_ISGID bit is set in the parent
* directory, group of new file is set to that of the parent, and
* new subdirectory gets S_ISGID bit from parent.
@@ -447,6 +453,9 @@ int xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset,
xfs_fsize_t isize, bool *did_zeroing);
int xfs_zero_range(struct xfs_inode *ip, xfs_off_t pos, xfs_off_t count,
bool *did_zero);
+int xfs_break_layouts(struct inode *inode, uint *iolock,
+ unsigned long flags);
+

/* from xfs_iops.c */
extern void xfs_setup_inode(struct xfs_inode *ip);
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 89fb1eb80aae..31288d900c8a 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -39,7 +39,6 @@
#include "xfs_icache.h"
#include "xfs_symlink.h"
#include "xfs_trans.h"
-#include "xfs_pnfs.h"
#include "xfs_acl.h"
#include "xfs_btree.h"
#include <linux/fsmap.h>
@@ -614,7 +613,7 @@ 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;

/*
@@ -644,13 +643,11 @@ xfs_ioc_space(
return error;

xfs_ilock(ip, iolock);
- error = xfs_break_layouts(inode, &iolock);
+ error = xfs_break_layouts(inode, &iolock,
+ XFS_BREAK_REMOTE | XFS_BREAK_MAPS);
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..15a1c7c874d9 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -37,7 +37,6 @@
#include "xfs_da_btree.h"
#include "xfs_dir2.h"
#include "xfs_trans_space.h"
-#include "xfs_pnfs.h"
#include "xfs_iomap.h"

#include <linux/capability.h>
@@ -1030,11 +1029,14 @@ xfs_vn_setattr(
struct xfs_inode *ip = XFS_I(d_inode(dentry));
uint iolock = XFS_IOLOCK_EXCL;

- error = xfs_break_layouts(d_inode(dentry), &iolock);
- if (error)
- return error;
-
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
+ error = xfs_break_layouts(d_inode(dentry), &iolock,
+ XFS_BREAK_REMOTE | XFS_BREAK_MAPS);
+
+ if (error) {
+ xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
+ return error;
+ }
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..ed13c9baffff 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -31,15 +31,13 @@
* rules in the page fault path we don't bother.
*/
int
-xfs_break_layouts(
+xfs_break_leased_layouts(
struct inode *inode,
uint *iolock)
{
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);
error = break_layout(inode, true);
@@ -120,8 +118,8 @@ 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);

diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
index bf45951e28fe..12f46fe6d902 100644
--- a/fs/xfs/xfs_pnfs.h
+++ b/fs/xfs/xfs_pnfs.h
@@ -9,10 +9,10 @@ int xfs_fs_map_blocks(struct inode *inode, loff_t offset, u64 length,
int xfs_fs_commit_blocks(struct inode *inode, struct iomap *maps, int nr_maps,
struct iattr *iattr);

-int xfs_break_layouts(struct inode *inode, uint *iolock);
+int xfs_break_leased_layouts(struct inode *inode, uint *iolock);
#else
static inline int
-xfs_break_layouts(struct inode *inode, uint *iolock)
+xfs_break_leased_layouts(struct inode *inode, uint *iolock)
{
return 0;
}
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