readahead: put limit on files we read ahead

src/readahead-collect.c

@@ -255,6 +255,9 @@ static int collect(const char *root) {
                 ssize_t n;
                 struct fanotify_event_metadata *m;
 
+                if (hashmap_size(files) > READAHEAD_FILES_MAX)
+                        break;
+
                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 
                         if (errno == EINTR)

src/readahead-common.h

@@ -25,6 +25,7 @@
 #include <sys/stat.h>
 
 #define READAHEAD_FILE_SIZE_MAX (128*1024*1024)
+#define READAHEAD_FILES_MAX (16*1024)
 
 int file_verify(int fd, const char *fn, struct stat *st);