get_hugepage_dir() was implemented in such a way that a --huge-dir option had to
exactly match the mountpoint, but there's no reason for this restriction. Fix
the implementation to allow a sub-directory within a suitable hugetlbfs
mountpoint to be specified, preferring the closest match.

Signed-off-by: John Levon <john.le...@nutanix.com>
---
 lib/eal/linux/eal_hugepage_info.c | 74 +++++++++++++++++++++----------
 1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/lib/eal/linux/eal_hugepage_info.c 
b/lib/eal/linux/eal_hugepage_info.c
index d97792cad..b5f08e94d 100644
--- a/lib/eal/linux/eal_hugepage_info.c
+++ b/lib/eal/linux/eal_hugepage_info.c
@@ -213,8 +213,8 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int 
len)
        const size_t pagesize_opt_len = sizeof(pagesize_opt) - 1;
        const char split_tok = ' ';
        char *splitstr[_FIELDNAME_MAX];
+       char found[PATH_MAX] = "";
        char buf[BUFSIZ];
-       int retval = -1;
        const struct internal_config *internal_conf =
                eal_get_internal_configuration();
 
@@ -226,42 +226,70 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int 
len)
                default_size = get_default_hp_size();
 
        while (fgets(buf, sizeof(buf), fd)){
+               const char *pagesz_str;
+
                if (rte_strsplit(buf, sizeof(buf), splitstr, _FIELDNAME_MAX,
                                split_tok) != _FIELDNAME_MAX) {
                        RTE_LOG(ERR, EAL, "Error parsing %s\n", proc_mounts);
                        break; /* return NULL */
                }
 
-               /* we have a specified --huge-dir option, only examine that dir 
*/
-               if (internal_conf->hugepage_dir != NULL &&
-                               strcmp(splitstr[MOUNTPT], 
internal_conf->hugepage_dir) != 0)
+               if (strncmp(splitstr[FSTYPE], hugetlbfs_str, htlbfs_str_len) != 
0) {
                        continue;
+               }
 
-               if (strncmp(splitstr[FSTYPE], hugetlbfs_str, htlbfs_str_len) == 
0){
-                       const char *pagesz_str = strstr(splitstr[OPTIONS], 
pagesize_opt);
+               pagesz_str = strstr(splitstr[OPTIONS], pagesize_opt);
 
-                       /* if no explicit page size, the default page size is 
compared */
-                       if (pagesz_str == NULL){
-                               if (hugepage_sz == default_size){
-                                       strlcpy(hugedir, splitstr[MOUNTPT], 
len);
-                                       retval = 0;
-                                       break;
-                               }
+               /* if no explicit page size, the default page size is compared 
*/
+               if (pagesz_str == NULL) {
+                       if (hugepage_sz != default_size) {
+                               continue;
                        }
-                       /* there is an explicit page size, so check it */
-                       else {
-                               uint64_t pagesz = 
rte_str_to_size(&pagesz_str[pagesize_opt_len]);
-                               if (pagesz == hugepage_sz) {
-                                       strlcpy(hugedir, splitstr[MOUNTPT], 
len);
-                                       retval = 0;
-                                       break;
-                               }
+               }
+               /* there is an explicit page size, so check it */
+               else {
+                       uint64_t pagesz = 
rte_str_to_size(&pagesz_str[pagesize_opt_len]);
+                       if (pagesz != hugepage_sz) {
+                               continue;
                        }
-               } /* end if strncmp hugetlbfs */
+               }
+
+               /*
+                * If no --huge-dir option has been given, we're done.
+                */
+               if (internal_conf->hugepage_dir == NULL) {
+                       strlcpy(found, splitstr[MOUNTPT], len);
+                       break;
+               }
+
+               /*
+                * Ignore any mount that doesn't contain the --huge-dir
+                * directory.
+                */
+               if (strncmp(internal_conf->hugepage_dir, splitstr[MOUNTPT],
+                       strlen(splitstr[MOUNTPT])) != 0) {
+                       continue;
+               }
+
+               /*
+                * We found a match, but only prefer it if it's a longer match
+                * (so /mnt/1 is preferred over /mnt for matching /mnt/1/2)).
+                */
+               if (strlen(splitstr[MOUNTPT]) > strlen(found)) {
+                       strlcpy(found, splitstr[MOUNTPT], len);
+               }
        } /* end while fgets */
 
        fclose(fd);
-       return retval;
+
+       if (found[0] != '\0') {
+               /* If needed, return the requested dir, not the mount point. */
+               strlcpy(hugedir, internal_conf->hugepage_dir != NULL ?
+                       internal_conf->hugepage_dir : found, len);
+               return 0;
+       }
+
+       return -1;
 }
 
 /*
-- 
2.25.1

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