LU-12785 dom: fix DoM component deletion code

[fs/lustre-release.git] / lustre / lod / lod_lov.c

diff --git a/lustre/lod/lod_lov.c b/lustre/lod/lod_lov.c
index a023959..9861040 100644 (file)
--- a/lustre/lod/lod_lov.c
+++ b/lustre/lod/lod_lov.c
@@ -1608,40 +1608,51 @@ int lod_erase_dom_stripe(struct lov_comp_md_v1 *comp_v1,
 {
        struct lov_comp_md_entry_v1 *ent;
        __u16 entries;
-       __u32 dom_off, dom_size, comp_size;
-       void *blob_src, *blob_dst;
-       unsigned int blob_size, blob_shift;
+       __u32 dom_off, dom_size, comp_size, off;
+       void *src, *dst;
+       unsigned int size, shift;
 
        entries = le16_to_cpu(comp_v1->lcm_entry_count) - 1;
-       /* if file has only DoM stripe return just error */
-       if (entries == 0)
-               return -EFBIG;
+       LASSERT(entries > 0);
+       comp_v1->lcm_entry_count = cpu_to_le16(entries);
 
        comp_size = le32_to_cpu(comp_v1->lcm_size);
        dom_off = le32_to_cpu(dom_ent->lcme_offset);
        dom_size = le32_to_cpu(dom_ent->lcme_size);
 
-       /* shift entries array first */
-       comp_v1->lcm_entry_count = cpu_to_le16(entries);
-       memmove(dom_ent, dom_ent + 1,
-               entries * sizeof(struct lov_comp_md_entry_v1));
-
-       /* now move blob of layouts */
-       blob_dst = (void *)comp_v1 + dom_off - sizeof(*dom_ent);
-       blob_src = (void *)comp_v1 + dom_off + dom_size;
-       blob_size = (unsigned long)((void *)comp_v1 + comp_size - blob_src);
-       blob_shift = sizeof(*dom_ent) + dom_size;
-
-       memmove(blob_dst, blob_src, blob_size);
-
+       /* all entries offsets are shifted by entry size at least */
+       shift = sizeof(*dom_ent);
        for_each_comp_entry_v1(comp_v1, ent) {
-               __u32 off;
-
                off = le32_to_cpu(ent->lcme_offset);
-               ent->lcme_offset = cpu_to_le32(off - blob_shift);
+               if (off == dom_off) {
+                       /* Entry deletion creates two holes in layout data:
+                        * - hole in entries array
+                        * - hole in layout data at dom_off with dom_size
+                        *
+                        * First memmove is one entry shift from next entry
+                        * start with size up to dom_off in blob
+                        */
+                       dst = (void *)ent;
+                       src = (void *)(ent + 1);
+                       size = (unsigned long)((void *)comp_v1 + dom_off - src);
+                       memmove(dst, src, size);
+                       /* take 'off' from just moved entry */
+                       off = le32_to_cpu(ent->lcme_offset);
+                       /* second memmove is blob tail after 'off' up to
+                        * component end
+                        */
+                       dst = (void *)comp_v1 + dom_off - sizeof(*ent);
+                       src = (void *)comp_v1 + off;
+                       size = (unsigned long)(comp_size - off);
+                       memmove(dst, src, size);
+                       /* all entries offsets after DoM entry are shifted by
+                        * dom_size additionally
+                        */
+                       shift += dom_size;
+               }
+               ent->lcme_offset = cpu_to_le32(off - shift);
        }
-
-       comp_v1->lcm_size = cpu_to_le32(comp_size - blob_shift);
+       comp_v1->lcm_size = cpu_to_le32(comp_size - shift);
 
        /* notify a caller to re-check entry */
        return -ERESTART;
@@ -1728,6 +1739,7 @@ int lod_dom_stripesize_choose(const struct lu_env *env, struct lod_device *d,
        __u32 max_stripe_size;
        __u16 mid, dom_mid;
        int rc = 0;
+       bool dom_next_entry = false;
 
        dom_ext = &dom_ent->lcme_extent;
        dom_mid = mirror_id_of(le32_to_cpu(dom_ent->lcme_id));
@@ -1742,6 +1754,10 @@ int lod_dom_stripesize_choose(const struct lu_env *env, struct lod_device *d,
               stripe_size, max_stripe_size);
        lum->lmm_stripe_size = cpu_to_le32(max_stripe_size);
 
+       /* In common case the DoM stripe is first entry in a mirror and
+        * can be deleted only if it is not single entry in layout or
+        * mirror, otherwise error should be returned.
+        */
        for_each_comp_entry_v1(comp_v1, ent) {
                if (ent == dom_ent)
                        continue;
@@ -1762,12 +1778,19 @@ int lod_dom_stripesize_choose(const struct lu_env *env, struct lod_device *d,
                 * always and don't need adjustment since use own layouts.
                 */
                ext->e_start = cpu_to_le64(max_stripe_size);
+               dom_next_entry = true;
                break;
        }
 
        if (max_stripe_size == 0) {
-               /* DoM component size is zero due to server setting,
-                * remove it from the layout */
+               /* DoM component size is zero due to server setting, remove
+                * it from the layout but only if next component exists in
+                * the same mirror. That must be checked prior calling the
+                * lod_erase_dom_stripe().
+                */
+               if (!dom_next_entry)
+                       return -EFBIG;
+
                rc = lod_erase_dom_stripe(comp_v1, dom_ent);
        } else {
                /* Update DoM extent end finally */