LU-2017 mdc: add layout swap between 2 objects

[fs/lustre-release.git] / lustre / llite / vvp_io.c

diff --git a/lustre/llite/vvp_io.c b/lustre/llite/vvp_io.c
index 18e30b6..9020d77 100644 (file)
--- a/lustre/llite/vvp_io.c
+++ b/lustre/llite/vvp_io.c
@@ -65,6 +65,39 @@ int cl_is_normalio(const struct lu_env *env, const struct cl_io *io)
         return vio->cui_io_subtype == IO_NORMAL;
 }
 
+/**
+ * For swapping layout. The file's layout may have changed.
+ * To avoid populating pages to a wrong stripe, we have to verify the
+ * correctness of layout. It works because swapping layout processes
+ * have to acquire group lock.
+ */
+static bool can_populate_pages(const struct lu_env *env, struct cl_io *io,
+                               struct inode *inode)
+{
+       struct ll_inode_info    *lli = ll_i2info(inode);
+       struct ccc_io           *cio = ccc_env_io(env);
+       bool rc = true;
+
+       switch (io->ci_type) {
+       case CIT_READ:
+       case CIT_WRITE:
+               /* don't need lock here to check lli_layout_gen as we have held
+                * extent lock and GROUP lock has to hold to swap layout */
+               if (lli->lli_layout_gen != cio->cui_layout_gen) {
+                       io->ci_need_restart = 1;
+                       /* this will return application a short read/write */
+                       io->ci_continue = 0;
+                       rc = false;
+               }
+       case CIT_FAULT:
+               /* fault is okay because we've already had a page. */
+       default:
+               break;
+       }
+
+       return rc;
+}
+
 /*****************************************************************************
  *
  * io operations.
@@ -452,6 +485,9 @@ static int vvp_io_read_start(const struct lu_env *env,
 
         CDEBUG(D_VFSTRACE, "read: -> [%lli, %lli)\n", pos, pos + cnt);
 
+       if (!can_populate_pages(env, io, inode))
+               return 0;
+
         result = ccc_prep_size(env, obj, io, pos, tot, &exceed);
         if (result != 0)
                 return result;
@@ -542,6 +578,9 @@ static int vvp_io_write_start(const struct lu_env *env,
 
         ENTRY;
 
+       if (!can_populate_pages(env, io, inode))
+               return 0;
+
         if (cl_io_is_append(io)) {
                 /*
                  * PARALLEL IO This has to be changed for parallel IO doing