LU-12518 llite: Accept EBUSY for page unaligned read

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

diff --git a/lustre/llite/rw.c b/lustre/llite/rw.c
index 61e8baf..2979d17 100644 (file)
--- a/lustre/llite/rw.c
+++ b/lustre/llite/rw.c
@@ -359,7 +359,8 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
                    struct ra_io_arg *ria, pgoff_t *ra_end)
 {
        struct cl_read_ahead ra = { 0 };
-       int rc = 0, count = 0;
+       /* busy page count is per stride */
+       int rc = 0, count = 0, busy_page_count = 0;
        pgoff_t page_idx;
 
        LASSERT(ria != NULL);
@@ -412,8 +413,20 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
 
                        /* If the page is inside the read-ahead window */
                        rc = ll_read_ahead_page(env, io, queue, page_idx);
-                       if (rc < 0)
+                       if (rc < 0 && rc != -EBUSY)
                                break;
+                       if (rc == -EBUSY) {
+                               busy_page_count++;
+                               CDEBUG(D_READA,
+                                      "skip busy page: %lu\n", page_idx);
+                               /* For page unaligned readahead the first
+                                * last pages of each region can be read by
+                                * another reader on the same node, and so
+                                * may be busy. So only stop for > 2 busy
+                                * pages. */
+                               if (busy_page_count > 2)
+                                       break;
+                       }
 
                        *ra_end = page_idx;
                        /* Only subtract from reserve & count the page if we
@@ -436,6 +449,7 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
                                pos += (ria->ria_length - offset);
                                if ((pos >> PAGE_SHIFT) >= page_idx + 1)
                                        page_idx = (pos >> PAGE_SHIFT) - 1;
+                               busy_page_count = 0;
                                CDEBUG(D_READA,
                                       "Stride: jump %llu pages to %lu\n",
                                       ria->ria_length - offset, page_idx);