-/*
- * Adjust a set of pages, each page containing an array of lu_dirpages,
- * so that each page can be used as a single logical lu_dirpage.
- *
- * A lu_dirpage is laid out as follows, where s = ldp_hash_start,
- * e = ldp_hash_end, f = ldp_flags, p = padding, and each "ent" is a
- * struct lu_dirent. It has size up to LU_PAGE_SIZE. The ldp_hash_end
- * value is used as a cookie to request the next lu_dirpage in a
- * directory listing that spans multiple pages (two in this example):
- * ________
- * | |
- * .|--------v------- -----.
- * |s|e|f|p|ent|ent| ... |ent|
- * '--|-------------- -----' Each CFS_PAGE contains a single
- * '------. lu_dirpage.
- * .---------v------- -----.
- * |s|e|f|p|ent| 0 | ... | 0 |
- * '----------------- -----'
- *
- * However, on hosts where the native VM page size (PAGE_CACHE_SIZE) is
- * larger than LU_PAGE_SIZE, a single host page may contain multiple
- * lu_dirpages. After reading the lu_dirpages from the MDS, the
- * ldp_hash_end of the first lu_dirpage refers to the one immediately
- * after it in the same CFS_PAGE (arrows simplified for brevity, but
- * in general e0==s1, e1==s2, etc.):
- *
- * .-------------------- -----.
- * |s0|e0|f0|p|ent|ent| ... |ent|
- * |---v---------------- -----|
- * |s1|e1|f1|p|ent|ent| ... |ent|
- * |---v---------------- -----| Here, each CFS_PAGE contains
- * ... multiple lu_dirpages.
- * |---v---------------- -----|
- * |s'|e'|f'|p|ent|ent| ... |ent|
- * '---|---------------- -----'
- * v
- * .----------------------------.
- * | next CFS_PAGE |
- *
- * This structure is transformed into a single logical lu_dirpage as follows:
- *
- * - Replace e0 with e' so the request for the next lu_dirpage gets the page
- * labeled 'next CFS_PAGE'.
- *
- * - Copy the LDF_COLLIDE flag from f' to f0 to correctly reflect whether
- * a hash collision with the next page exists.
- *
- * - Adjust the lde_reclen of the ending entry of each lu_dirpage to span
- * to the first entry of the next lu_dirpage.
- */
-#if PAGE_CACHE_SIZE > LU_PAGE_SIZE
-static void lmv_adjust_dirpages(struct page **pages, int ncfspgs, int nlupgs)
-{
- int i;
-
- for (i = 0; i < ncfspgs; i++) {
- struct lu_dirpage *dp = kmap(pages[i]);
- struct lu_dirpage *first = dp;
- struct lu_dirent *end_dirent = NULL;
- struct lu_dirent *ent;
- __u64 hash_end = dp->ldp_hash_end;
- __u32 flags = dp->ldp_flags;
-
- while (--nlupgs > 0) {
- ent = lu_dirent_start(dp);
- for (end_dirent = ent; ent != NULL;
- end_dirent = ent, ent = lu_dirent_next(ent));
-
- /* Advance dp to next lu_dirpage. */
- dp = (struct lu_dirpage *)((char *)dp + LU_PAGE_SIZE);
-
- /* Check if we've reached the end of the CFS_PAGE. */
- if (!((unsigned long)dp & ~CFS_PAGE_MASK))
- break;
-
- /* Save the hash and flags of this lu_dirpage. */
- hash_end = dp->ldp_hash_end;
- flags = dp->ldp_flags;
-
- /* Check if lu_dirpage contains no entries. */
- if (!end_dirent)
- break;
-
- /* Enlarge the end entry lde_reclen from 0 to
- * first entry of next lu_dirpage. */
- LASSERT(le16_to_cpu(end_dirent->lde_reclen) == 0);
- end_dirent->lde_reclen =
- cpu_to_le16((char *)(dp->ldp_entries) -
- (char *)end_dirent);
- }
-
- first->ldp_hash_end = hash_end;
- first->ldp_flags &= ~cpu_to_le32(LDF_COLLIDE);
- first->ldp_flags |= flags & cpu_to_le32(LDF_COLLIDE);
-
- kunmap(pages[i]);
- }
- LASSERTF(nlupgs == 0, "left = %d", nlupgs);
-}
-#else
-#define lmv_adjust_dirpages(pages, ncfspgs, nlupgs) do {} while (0)
-#endif /* PAGE_CACHE_SIZE > LU_PAGE_SIZE */
-