[uml-devel] hostfs leaks file descriptors

[uml-devel] hostfs leaks file descriptors

[Ingo van Lil]

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Hi there,

when hostfs is used as the UML's root filesystem its file descriptors 
aren't closed when the kernel is rebooted. Subsequently, after a couple 
of reboots the guest will reach the maximum number of allowed file 
descriptors (usually 1024) and fail to open any more files.

I tried to fix the problem myself, see patch. It works for me, but I'm 
not sure if it's the correct solution.

Cheers,
Ingo

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Index: hostfs_kern.c
===================================================================
--- hostfs_kern.c	(revision 8135)
+++ hostfs_kern.c	(working copy)
@@ -16,6 +16,7 @@
 #include <linux/list.h>
 #include <linux/statfs.h>
 #include <linux/kdev_t.h>
+#include <linux/mount.h>
 #include <asm/uaccess.h>
 #include "hostfs.h"
 #include "kern_util.h"
@@ -1037,3 +1038,17 @@
 module_init(init_hostfs)
 module_exit(exit_hostfs)
 MODULE_LICENSE("GPL");
+
+static void hostfs_exitcall(void)
+{
+	struct super_block *root_sb = current->fs->rootmnt->mnt_sb;
+	if (root_sb->s_type == &hostfs_type) {
+		struct inode *inode;
+		list_for_each_entry(inode, &root_sb->s_inodes, i_sb_list) {
+			if(HOSTFS_I(inode)->fd != -1) {
+				close_file(&HOSTFS_I(inode)->fd);
+			}
+		}
+	}
+}
+__uml_exitcall(hostfs_exitcall);

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