[Minios-devel] [UNIKRAFT PATCH 1/3] lib/vfscore: Use a scalable bitmap for open file descriptors

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Until now, the number of open file descriptors was limited to 64, which was the
number of bits of the underlying bitmap. We fix that by replacing with a
configurable bitmap. We set the default value of maximum open files to 1024.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
 lib/vfscore/Config.uk |  8 +++++++-
 lib/vfscore/fd.c      | 16 ++++++++--------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/lib/vfscore/Config.uk b/lib/vfscore/Config.uk
index 6cf6c63a..07319099 100644
--- a/lib/vfscore/Config.uk
+++ b/lib/vfscore/Config.uk
@@ -1,6 +1,12 @@
-config LIBVFSCORE
+menuconfig LIBVFSCORE
        bool "vfscore: VFS Core Interface"
        default n
        select LIBNOLIBC if !HAVE_LIBC
        select LIBUKDEBUG
        select LIBUKLOCK
+
+if LIBVFSCORE
+config LIBVFSCORE_MAX_FILES
+       int "Maximum number of open files"
+       default 1024
+endif
diff --git a/lib/vfscore/fd.c b/lib/vfscore/fd.c
index 01025a46..e09dd54c 100644
--- a/lib/vfscore/fd.c
+++ b/lib/vfscore/fd.c
@@ -35,19 +35,19 @@
 
 #include <string.h>
 #include <uk/essentials.h>
-#include <uk/bitops.h>
+#include <uk/bitmap.h>
 #include <uk/assert.h>
 #include <vfscore/file.h>
 #include <uk/plat/lcpu.h>
 #include <errno.h>
 #include <uk/ctors.h>
 
-#define FDTABLE_MAX_FILES (sizeof(uint64_t) * 8)
+#define FDTABLE_MAX_FILES 1024
 
 void init_stdio(void);
 
 struct fdtable {
-       uint64_t bitmap;
+       unsigned long bitmap[UK_BITS_TO_LONGS(FDTABLE_MAX_FILES)];
        uint32_t fd_start;
        struct vfscore_file *files[FDTABLE_MAX_FILES];
 };
@@ -59,14 +59,14 @@ int vfscore_alloc_fd(void)
        int ret;
 
        flags = ukplat_lcpu_save_irqf();
-       ret = ukarch_ffsl(~fdtable.bitmap);
+       ret = uk_find_next_zero_bit(fdtable.bitmap, FDTABLE_MAX_FILES, 0);
 
        if (!ret) {
                ret = -ENFILE;
                goto exit;
        }
 
-       fdtable.bitmap |= (uint64_t) 1 << ret;
+       uk_bitmap_set(fdtable.bitmap, ret, 1);
 
 exit:
        ukplat_lcpu_restore_irqf(flags);
@@ -83,7 +83,7 @@ void vfscore_put_fd(int fd)
        UK_ASSERT(fd > 2);
 
        flags = ukplat_lcpu_save_irqf();
-       __uk_clear_bit(fd, &fdtable.bitmap);\
+       uk_bitmap_clear(fdtable.bitmap, fd, 1);
        fp = fdtable.files[fd];
        fdtable.files[fd] = NULL;
        ukplat_lcpu_restore_irqf(flags);
@@ -129,7 +129,7 @@ struct vfscore_file *vfscore_get_file(int fd)
        UK_ASSERT(fd < (int) FDTABLE_MAX_FILES);
 
        flags = ukplat_lcpu_save_irqf();
-       if (!(fdtable.bitmap & ((uint64_t) 1 << fd)))
+       if (!uk_test_bit(fd, fdtable.bitmap))
                goto exit;
        ret = fdtable.files[fd];
        fhold(ret);
@@ -186,7 +186,7 @@ static void fdtable_init(void)
        memset(&fdtable, 0, sizeof(fdtable));
 
        /* reserve stdin, stdout and stderr */
-       fdtable.bitmap = 7;
+       uk_bitmap_set(fdtable.bitmap, 0, 3);
        init_stdio();
 }
 
-- 
2.20.1


_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/minios-devel