xfs: recall pNFS layouts on conflicting access

Recall all outstanding pNFS layouts and truncates, writes and similar extent
list modifying operations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

5 files changed, 64 insertions, 7 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 712d312d8e3e..56dcfce8d7d6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -36,6 +36,7 @@
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_icache.h"
+#include "xfs_pnfs.h"
 
 #include <linux/aio.h>
 #include <linux/dcache.h>
@@ -554,6 +555,10 @@ restart:
         if (error)
                 return error;
 
+        error = xfs_break_layouts(inode, iolock);
+        if (error)
+                return error;
+
         /*
          * If the offset is beyond the size of the file, we need to zero any
          * blocks that fall between the existing EOF and the start of this
@@ -822,6 +827,7 @@ xfs_file_fallocate(
         struct xfs_inode        *ip = XFS_I(inode);
         long                    error;
         enum xfs_prealloc_flags flags = 0;
+        uint                    iolock = XFS_IOLOCK_EXCL;
         loff_t                  new_size = 0;
 
         if (!S_ISREG(inode->i_mode))
@@ -830,7 +836,11 @@ xfs_file_fallocate(
                      FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
                 return -EOPNOTSUPP;
 
-        xfs_ilock(ip, XFS_IOLOCK_EXCL);
+        xfs_ilock(ip, iolock);
+        error = xfs_break_layouts(inode, &iolock);
+        if (error)
+                goto out_unlock;
+
         if (mode & FALLOC_FL_PUNCH_HOLE) {
                 error = xfs_free_file_space(ip, offset, len);
                 if (error)
@@ -894,7 +904,7 @@ xfs_file_fallocate(
         }
 
 out_unlock:
-        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+        xfs_iunlock(ip, iolock);
         return error;
 }
 
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index f7afb86c9148..bf70a2affb05 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -39,6 +39,7 @@
 #include "xfs_icache.h"
 #include "xfs_symlink.h"
 #include "xfs_trans.h"
+#include "xfs_pnfs.h"
 
 #include <linux/capability.h>
 #include <linux/dcache.h>
@@ -608,6 +609,7 @@ xfs_ioc_space(
 {
         struct iattr            iattr;
         enum xfs_prealloc_flags flags = 0;
+        uint                    iolock = XFS_IOLOCK_EXCL;
         int                     error;
 
         /*
@@ -636,7 +638,10 @@ xfs_ioc_space(
         if (error)
                 return error;
 
-        xfs_ilock(ip, XFS_IOLOCK_EXCL);
+        xfs_ilock(ip, iolock);
+        error = xfs_break_layouts(inode, &iolock);
+        if (error)
+                goto out_unlock;
 
         switch (bf->l_whence) {
         case 0: /*SEEK_SET*/
@@ -725,7 +730,7 @@ xfs_ioc_space(
         error = xfs_update_prealloc_flags(ip, flags);
 
 out_unlock:
-        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+        xfs_iunlock(ip, iolock);
         mnt_drop_write_file(filp);
         return error;
 }
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index e5e2ea0d0b25..d919ad7b16bf 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -37,6 +37,7 @@
 #include "xfs_da_btree.h"
 #include "xfs_dir2.h"
 #include "xfs_trans_space.h"
+#include "xfs_pnfs.h"
 
 #include <linux/capability.h>
 #include <linux/xattr.h>
@@ -979,9 +980,13 @@ xfs_vn_setattr(
         int                     error;
 
         if (iattr->ia_valid & ATTR_SIZE) {
-                xfs_ilock(ip, XFS_IOLOCK_EXCL);
-                error = xfs_setattr_size(ip, iattr);
-                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+                uint            iolock = XFS_IOLOCK_EXCL;
+
+                xfs_ilock(ip, iolock);
+                error = xfs_break_layouts(dentry->d_inode, &iolock);
+                if (!error)
+                        error = xfs_setattr_size(ip, iattr);
+                xfs_iunlock(ip, iolock);
         } else {
                 error = xfs_setattr_nonsize(ip, iattr, 0);
         }
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 89912b34f184..4b33ef112400 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -19,6 +19,36 @@
 #include "xfs_pnfs.h"
 
 /*
+ * Ensure that we do not have any outstanding pNFS layouts that can be used by
+ * clients to directly read from or write to this inode.  This must be called
+ * before every operation that can remove blocks from the extent map.
+ * Additionally we call it during the write operation, where aren't concerned
+ * about exposing unallocated blocks but just want to provide basic
+ * synchronization between a local writer and pNFS clients.  mmap writes would
+ * also benefit from this sort of synchronization, but due to the tricky locking
+ * rules in the page fault path we don't bother.
+ */
+int
+xfs_break_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);
+                *iolock = XFS_IOLOCK_EXCL;
+                xfs_ilock(ip, *iolock);
+        }
+
+        return error;
+}
+
+/*
  * Get a unique ID including its location so that the client can identify
  * the exported device.
  */
diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
index 0d91255a89ae..b7fbfce660f6 100644
--- a/fs/xfs/xfs_pnfs.h
+++ b/fs/xfs/xfs_pnfs.h
@@ -7,5 +7,12 @@ int xfs_fs_map_blocks(struct inode *inode, loff_t offset, u64 length,
                 struct iomap *iomap, bool write, u32 *device_generation);
 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);
+#else
+static inline int xfs_break_layouts(struct inode *inode, uint *iolock)
+{
+        return 0;
+}
 #endif /* CONFIG_NFSD_PNFS */
 #endif /* _XFS_PNFS_H */