swap: Tweak meminfo logic

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/proc_fuse.c b/src/proc_fuse.c
index 002aac9f472e60f3316683faed1377492ab18a6e..4c555ec26e018ec2eb747685451f0e33e1cda3c8 100644 (file)
--- a/src/proc_fuse.c
+++ b/src/proc_fuse.c
@@ -1151,7 +1151,7 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
        __do_fclose FILE *f = NULL;
        struct fuse_context *fc = fuse_get_context();
        struct lxcfs_opts *opts = (struct lxcfs_opts *)fuse_get_context()->private_data;
-       bool wants_swap = opts && !opts->swap_off && liblxcfs_can_use_swap(), host_swap = false;
+       bool wants_swap = opts && !opts->swap_off && liblxcfs_can_use_swap();
        struct file_info *d = INTTYPE_TO_PTR(fi->fh);
        uint64_t memlimit = 0, memusage = 0, memswlimit = 0, memswusage = 0,
                 hosttotal = 0, swfree = 0, swusage = 0, swtotal = 0,
@@ -1258,19 +1258,14 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
 
                                sscanf(line + STRLITERALLEN("SwapTotal:"), "%" PRIu64, &hostswtotal);
 
-                               /*
-                                * If swtotal is 0 it should mean that
-                                * memory.memsw.limit_in_bytes and
-                                * memory.limit_in_bytes are both unlimited or
-                                * both set to the same value. In both cases we
-                                * have no idea what the technical swap limit
-                                * is supposed to be (It's a shared limit
-                                * anyway.) so fallback to the host's values in
-                                * that case too.
-                                */
-                               if ((hostswtotal < swtotal) || swtotal == 0) {
+                               /* The total amount of swap is always reported to be the
+                                  lesser of the RAM+SWAP limit or the SWAP device size.
+                                  This is because the kernel can swap as much as it
+                                  wants and not only up to swtotal. */
+
+                               swtotal = memlimit + swtotal;
+                               if (hostswtotal < swtotal) {
                                        swtotal = hostswtotal;
-                                       host_swap = true;
                                }
 
                                /* When swappiness is 0, pretend we can't swap. */
@@ -1283,14 +1278,7 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
                        printme = lbuf;
                } else if (startswith(line, "SwapFree:")) {
                        if (wants_swap) {
-                               uint64_t hostswfree = 0;
-
-                               if (host_swap) {
-                                       sscanf(line + STRLITERALLEN("SwapFree:"), "%" PRIu64, &hostswfree);
-                                       swfree = hostswfree;
-                               } else if (swtotal >= swusage) {
-                                       swfree = swtotal - swusage;
-                               }
+                               swfree = swtotal - swusage;
                        }
 
                        snprintf(lbuf, 100, "SwapFree:       %8" PRIu64 " kB\n", swfree);