lkml.org 
[lkml]   [2003]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRootfs mounted from user space - problem with umount
I modified my kernel so that rootfs uses tmpfs (shm) instead of ramfs.  
I also modified it so that it allows mounting from user space. My
problem is when I try to umount it, umount hangs. I checked it's
proc/#/wchan entry and it's stuck in rwsem_down_write_failed. Now the
strange thing is I can mount it again from another console and then
umount it with no problems. It just hangs the first time. I know I'm
missing something simple but I can't seem to find it.

Here's the mods I made:

diff -urNX dontdiff linux.old/drivers/block/Kconfig linux/drivers/block/Kconfig
--- linux.old/drivers/block/Kconfig 2003-10-25 14:43:07.000000000 -0400
+++ linux/drivers/block/Kconfig 2003-11-28 23:43:05.000000000 -0500
@@ -320,6 +320,24 @@
"real" root file system, etc. See <file:Documentation/initrd.txt>
for details.

+config SHM_ROOTFS
+ bool "Use tmpfs (shm) instead of ramfs for rootfs"
+ depends on BLK_DEV_INITRD
+ default n
+ help
+ This option switches rootfs so that it uses tmpfs rather than ramfs
+ for it's file storage. This makes rootfs swappable so having a large
+ initrd or initramfs image won't eat up valuable RAM.
+
+ You don't have to select the tmpfs option in the file system menu
+ as that's only for user space mounting.
+
+config RAMFS_ROOTFS
+ bool
+ depends on !SHM_ROOTFS
+ default y
+ select RAMFS
+
config LBD
bool "Support for Large Block Devices"
depends on X86 || MIPS32 || PPC32 || ARCH_S390_31 || SUPERH
diff -urNX dontdiff linux.old/fs/Kconfig linux/fs/Kconfig
--- linux.old/fs/Kconfig 2003-10-25 14:43:51.000000000 -0400
+++ linux/fs/Kconfig 2003-11-28 23:20:48.000000000 -0500
@@ -879,8 +879,8 @@
config HUGETLB_PAGE
def_bool HUGETLBFS

-config RAMFS
- bool
+config RAMFS
+ tristate "Ramfs file system support"
default y
---help---
Ramfs is a file system which keeps all files in RAM. It allows
diff -urNX dontdiff linux.old/fs/ramfs/inode.c linux/fs/ramfs/inode.c
--- linux.old/fs/ramfs/inode.c 2003-10-25 14:43:21.000000000 -0400
+++ linux/fs/ramfs/inode.c 2003-11-28 23:32:21.000000000 -0500
@@ -204,22 +204,26 @@
return get_sb_nodev(fs_type, flags, data, ramfs_fill_super);
}

+#ifdef CONFIG_RAMFS_ROOTFS
static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
}
+#endif

static struct file_system_type ramfs_fs_type = {
.name = "ramfs",
.get_sb = ramfs_get_sb,
.kill_sb = kill_litter_super,
};
+#ifdef CONFIG_RAMFS_ROOTFS
static struct file_system_type rootfs_fs_type = {
.name = "rootfs",
.get_sb = rootfs_get_sb,
.kill_sb = kill_litter_super,
};
+#endif

static int __init init_ramfs_fs(void)
{
@@ -234,9 +238,11 @@
module_init(init_ramfs_fs)
module_exit(exit_ramfs_fs)

+#ifdef CONFIG_RAMFS_ROOTFS
int __init init_rootfs(void)
{
return register_filesystem(&rootfs_fs_type);
}
+#endif

MODULE_LICENSE("GPL");
diff -urNX dontdiff linux.old/mm/shmem.c linux/mm/shmem.c
--- linux.old/mm/shmem.c 2003-10-25 14:43:30.000000000 -0400
+++ linux/mm/shmem.c 2003-11-29 00:00:37.000000000 -0500
@@ -1773,7 +1773,7 @@
sb->s_fs_info = NULL;
}

-static kmem_cache_t *shmem_inode_cachep;
+static kmem_cache_t *shmem_inode_cachep = NULL;

static struct inode *shmem_alloc_inode(struct super_block *sb)
{
@@ -1801,12 +1801,14 @@

static int init_inodecache(void)
{
- shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
- sizeof(struct shmem_inode_info),
- 0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
- init_once, NULL);
- if (shmem_inode_cachep == NULL)
- return -ENOMEM;
+ if (!shmem_inode_cachep) {
+ shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
+ sizeof(struct shmem_inode_info),
+ 0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
+ init_once, NULL);
+ if (shmem_inode_cachep == NULL)
+ return -ENOMEM;
+ }
return 0;
}

@@ -2008,3 +2010,29 @@
}

EXPORT_SYMBOL(shmem_file_setup);
+
+#ifdef CONFIG_SHM_ROOTFS
+static struct super_block *rootfs_sb = NULL;
+
+static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ if (!rootfs_sb) {
+ rootfs_sb = get_sb_single(fs_type, flags, data, shmem_fill_super);
+ shmem_set_size(SHMEM_SB(rootfs_sb), ULONG_MAX, ULONG_MAX);
+ }
+ return rootfs_sb;
+}
+
+static struct file_system_type rootfs_fs_type = {
+ .name = "rootfs",
+ .get_sb = rootfs_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+int __init init_rootfs(void)
+{
+ init_inodecache();
+ return register_filesystem(&rootfs_fs_type);
+}
+#endif

John



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:59    [W:0.093 / U:0.088 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site