[CFT][PATCH] superblock handling changes

Alexander Viro (viro@math.psu.edu)
Tue, 12 Jun 2001 00:29:04 -0400 (EDT)


Folks, the patch below the fixed and combined variant of
the last series of patches sent to Linus.

It does pretty heavy changes of fs/super.c mechanics and
since one of the chunks I've sent originally contained a trivial
bug I've missed during testing - it obviously need heavier beating
than I've done.

I'm reasonably sure that it is OK. Moreover, we need something
of that kind to fix a bunch of oopsable races. However, not introducing
new bugs would be a Good Thing(tm).

Please, help with testing and code review. I don't want to
send 11 patches (10 chunks + 1 combined), so I'm sending the combined
version in this posting and putting the split-up for review on
ftp.math.psu.edu/pub/viro/[0-9]*S6-pre2

Please, be careful with that one. _If_ it blows up it's more than
likely to leave box in a state when any activity on sync/mount/umount
stops dead. It is pretty straightforward (in split state) and I believe
that if there are bugs they will be easy to find, but until then...
Reviewing the code should be completely safe, though ;-) Seriously, I
think that it's OK, but I've missed one in it, so no warranties.

If it gets no complaints in a reasonable time I'm going to
resubmit it to Linus, so... Please, help testing it. And yes, I'll
keep torturing it myself (obviously).

Combined patch follows:

diff -urN S6-pre2/arch/parisc/hpux/sys_hpux.c S6-pre2-super/arch/parisc/hpux/sys_hpux.c
--- S6-pre2/arch/parisc/hpux/sys_hpux.c Fri Feb 16 20:46:44 2001
+++ S6-pre2-super/arch/parisc/hpux/sys_hpux.c Mon Jun 11 23:55:03 2001
@@ -109,9 +109,11 @@

lock_kernel();
s = get_super(to_kdev_t(dev));
+ unlock_kernel();
if (s == NULL)
goto out;
err = vfs_statfs(s, &sbuf);
+ drop_super(s);
if (err)
goto out;

@@ -124,7 +126,6 @@
/* Changed to hpux_ustat: */
err = copy_to_user(ubuf,&tmp,sizeof(struct hpux_ustat)) ? -EFAULT : 0;
out:
- unlock_kernel();
return err;
}

diff -urN S6-pre2/fs/block_dev.c S6-pre2-super/fs/block_dev.c
--- S6-pre2/fs/block_dev.c Fri Jun 8 18:29:02 2001
+++ S6-pre2-super/fs/block_dev.c Mon Jun 11 23:55:02 2001
@@ -678,8 +678,10 @@
down(&bdev->bd_sem);
/* syncing will go here */
lock_kernel();
- if (kind == BDEV_FILE || kind == BDEV_FS)
+ if (kind == BDEV_FILE)
fsync_dev(rdev);
+ else if (kind == BDEV_FS)
+ fsync_no_super(rdev);
if (atomic_dec_and_test(&bdev->bd_openers)) {
/* invalidating buffers will go here */
invalidate_buffers(rdev);
diff -urN S6-pre2/fs/buffer.c S6-pre2-super/fs/buffer.c
--- S6-pre2/fs/buffer.c Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/fs/buffer.c Mon Jun 11 23:55:02 2001
@@ -318,6 +318,12 @@
return sync_buffers(dev, 1);
}

+int fsync_no_super(kdev_t dev)
+{
+ sync_buffers(dev, 0);
+ return sync_buffers(dev, 1);
+}
+
int fsync_dev(kdev_t dev)
{
sync_buffers(dev, 0);
diff -urN S6-pre2/fs/dquot.c S6-pre2-super/fs/dquot.c
--- S6-pre2/fs/dquot.c Thu May 24 18:26:44 2001
+++ S6-pre2-super/fs/dquot.c Mon Jun 11 23:55:03 2001
@@ -325,7 +325,7 @@
memset(&dquot->dq_dqb, 0, sizeof(struct dqblk));
}

-void invalidate_dquots(kdev_t dev, short type)
+static void invalidate_dquots(kdev_t dev, short type)
{
struct dquot *dquot, *next;
int need_restart;
@@ -1388,7 +1388,7 @@
}

/* Function in inode.c - remove pointers to dquots in icache */
-extern void remove_dquot_ref(kdev_t, short);
+extern void remove_dquot_ref(struct super_block *, short);

/*
* Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
@@ -1413,7 +1413,7 @@
reset_enable_flags(dqopt, cnt);

/* Note: these are blocking operations */
- remove_dquot_ref(sb->s_dev, cnt);
+ remove_dquot_ref(sb, cnt);
invalidate_dquots(sb->s_dev, cnt);

/* Wait for any pending IO - remove me as soon as invalidate is more polite */
@@ -1602,6 +1602,8 @@
if (sb && sb_has_quota_enabled(sb, type))
ret = set_dqblk(sb, id, type, flags, (struct dqblk *) addr);
out:
+ if (sb)
+ drop_super(sb);
unlock_kernel();
return ret;
}
diff -urN S6-pre2/fs/inode.c S6-pre2-super/fs/inode.c
--- S6-pre2/fs/inode.c Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/fs/inode.c Mon Jun 11 23:55:03 2001
@@ -258,23 +258,6 @@
__sync_one(list_entry(tmp, struct inode, i_list), 0);
}

-static inline int wait_on_dirty(struct list_head *head)
-{
- struct list_head * tmp;
- list_for_each(tmp, head) {
- struct inode *inode = list_entry(tmp, struct inode, i_list);
- if (!inode->i_state & I_DIRTY)
- continue;
- __iget(inode);
- spin_unlock(&inode_lock);
- __wait_on_inode(inode);
- iput(inode);
- spin_lock(&inode_lock);
- return 1;
- }
- return 0;
-}
-
static inline void wait_on_locked(struct list_head *head)
{
struct list_head * tmp;
@@ -319,61 +302,96 @@
return 1;
}

-/**
- * sync_inodes
- * @dev: device to sync the inodes from.
- *
- * sync_inodes goes through the super block's dirty list,
- * writes them out, and puts them back on the normal list.
- */
-
-/*
- * caller holds exclusive lock on sb->s_umount
- */
-
void sync_inodes_sb(struct super_block *sb)
{
spin_lock(&inode_lock);
- sync_list(&sb->s_dirty);
- wait_on_locked(&sb->s_locked_inodes);
+ while (!list_empty(&sb->s_dirty)||!list_empty(&sb->s_locked_inodes)) {
+ sync_list(&sb->s_dirty);
+ wait_on_locked(&sb->s_locked_inodes);
+ }
spin_unlock(&inode_lock);
}

+/*
+ * Note:
+ * We don't need to grab a reference to superblock here. If it has non-empty
+ * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed
+ * past sync_inodes_sb() until both ->s_dirty and ->s_locked_inodes are
+ * empty. Since __sync_one() regains inode_lock before it finally moves
+ * inode from superblock lists we are OK.
+ */
+
void sync_unlocked_inodes(void)
{
- struct super_block * sb = sb_entry(super_blocks.next);
+ struct super_block * sb;
+ spin_lock(&inode_lock);
+ spin_lock(&sb_lock);
+ sb = sb_entry(super_blocks.next);
for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.next)) {
if (!list_empty(&sb->s_dirty)) {
- spin_lock(&inode_lock);
+ spin_unlock(&sb_lock);
sync_list(&sb->s_dirty);
- spin_unlock(&inode_lock);
+ spin_lock(&sb_lock);
}
}
+ spin_unlock(&sb_lock);
+ spin_unlock(&inode_lock);
}

+/*
+ * Find a superblock with inodes that need to be synced
+ */
+
+static struct super_block *get_super_to_sync(void)
+{
+ struct list_head *p;
+restart:
+ spin_lock(&inode_lock);
+ spin_lock(&sb_lock);
+ list_for_each(p, &super_blocks) {
+ struct super_block *s = list_entry(p,struct super_block,s_list);
+ if (list_empty(&s->s_dirty) && list_empty(&s->s_locked_inodes))
+ continue;
+ s->s_count++;
+ spin_unlock(&sb_lock);
+ spin_unlock(&inode_lock);
+ down_read(&s->s_umount);
+ if (!s->s_root) {
+ drop_super(s);
+ goto restart;
+ }
+ return s;
+ }
+ spin_unlock(&sb_lock);
+ spin_unlock(&inode_lock);
+ return NULL;
+}
+
+/**
+ * sync_inodes
+ * @dev: device to sync the inodes from.
+ *
+ * sync_inodes goes through the super block's dirty list,
+ * writes them out, and puts them back on the normal list.
+ */
+
void sync_inodes(kdev_t dev)
{
- struct super_block * sb = sb_entry(super_blocks.next);
+ struct super_block * s;

/*
* Search the super_blocks array for the device(s) to sync.
*/
- for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.next)) {
- if (!sb->s_dev)
- continue;
- if (dev && sb->s_dev != dev)
- continue;
- down_read(&sb->s_umount);
- if (sb->s_dev && (sb->s_dev == dev || !dev)) {
- spin_lock(&inode_lock);
- do {
- sync_list(&sb->s_dirty);
- } while (wait_on_dirty(&sb->s_locked_inodes));
- spin_unlock(&inode_lock);
+ if (dev) {
+ if ((s = get_super(dev)) != NULL) {
+ sync_inodes_sb(s);
+ drop_super(s);
+ }
+ } else {
+ while ((s = get_super_to_sync()) != NULL) {
+ sync_inodes_sb(s);
+ drop_super(s);
}
- up_read(&sb->s_umount);
- if (dev)
- break;
}
}

@@ -382,13 +400,19 @@
*/
static void try_to_sync_unused_inodes(void)
{
- struct super_block * sb = sb_entry(super_blocks.next);
+ struct super_block * sb;
+
+ spin_lock(&sb_lock);
+ sb = sb_entry(super_blocks.next);
for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.next)) {
if (!sb->s_dev)
continue;
+ spin_unlock(&sb_lock);
if (!try_to_sync_unused_list(&sb->s_dirty))
break;
+ spin_lock(&sb_lock);
}
+ spin_unlock(&sb_lock);
}

/**
@@ -598,15 +622,18 @@

int invalidate_device(kdev_t dev, int do_sync)
{
- struct super_block *sb = get_super(dev);
+ struct super_block *sb;
int res;

if (do_sync)
fsync_dev(dev);

res = 0;
- if (sb)
+ sb = get_super(dev);
+ if (sb) {
res = invalidate_inodes(sb);
+ drop_super(sb);
+ }
invalidate_buffers(dev);
return res;
}
@@ -1164,14 +1191,13 @@
void put_dquot_list(struct list_head *);
int remove_inode_dquot_ref(struct inode *, short, struct list_head *);

-void remove_dquot_ref(kdev_t dev, short type)
+void remove_dquot_ref(struct super_block *sb, short type)
{
- struct super_block *sb = get_super(dev);
struct inode *inode;
struct list_head *act_head;
LIST_HEAD(tofree_head);

- if (!sb || !sb->dq_op)
+ if (!sb->dq_op)
return; /* nothing to do */

/* We have to be protected against other CPUs */
diff -urN S6-pre2/fs/super.c S6-pre2-super/fs/super.c
--- S6-pre2/fs/super.c Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/fs/super.c Mon Jun 11 23:56:28 2001
@@ -59,9 +59,8 @@
/* this is initialized in init/main.c */
kdev_t ROOT_DEV;

-int nr_super_blocks;
-int max_super_blocks = NR_SUPER;
LIST_HEAD(super_blocks);
+spinlock_t sb_lock = SPIN_LOCK_UNLOCKED;

/*
* Handling of filesystem drivers list.
@@ -386,7 +385,6 @@
mnt->mnt_parent = mnt;

spin_lock(&dcache_lock);
- list_add(&mnt->mnt_instances, &sb->s_mounts);
list_add(&mnt->mnt_list, vfsmntlist.prev);
spin_unlock(&dcache_lock);
if (sb->s_type->fs_flags & FS_SINGLE)
@@ -395,10 +393,11 @@
return mnt;
}

-static struct vfsmount *clone_mnt(struct vfsmount *old_mnt, struct dentry *root)
+static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root)
{
- char *name = old_mnt->mnt_devname;
+ char *name = old->mnt_devname;
struct vfsmount *mnt = alloc_vfsmnt();
+ struct super_block *sb = old->mnt_sb;

if (!mnt)
goto out;
@@ -408,14 +407,12 @@
if (mnt->mnt_devname)
strcpy(mnt->mnt_devname, name);
}
- mnt->mnt_sb = old_mnt->mnt_sb;
+ mnt->mnt_sb = sb;
mnt->mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;

- spin_lock(&dcache_lock);
- list_add(&mnt->mnt_instances, &old_mnt->mnt_instances);
- spin_unlock(&dcache_lock);
+ atomic_inc(&sb->s_active);
out:
return mnt;
}
@@ -487,16 +484,12 @@
struct super_block *sb = mnt->mnt_sb;

dput(mnt->mnt_root);
- spin_lock(&dcache_lock);
- list_del(&mnt->mnt_instances);
- spin_unlock(&dcache_lock);
if (mnt->mnt_devname)
kfree(mnt->mnt_devname);
kmem_cache_free(mnt_cache, mnt);
kill_super(sb);
}

-
/* Use octal escapes, like mount does, for embedded spaces etc. */
static unsigned char need_escaping[] = { ' ', '\t', '\n', '\\' };

@@ -645,6 +638,49 @@
#undef MANGLE
#undef FREEROOM
}
+
+static inline void __put_super(struct super_block *sb)
+{
+ spin_lock(&sb_lock);
+ if (!--sb->s_count)
+ kfree(sb);
+ spin_unlock(&sb_lock);
+}
+
+static inline struct super_block * find_super(kdev_t dev)
+{
+ struct list_head *p;
+
+ list_for_each(p, &super_blocks) {
+ struct super_block * s = sb_entry(p);
+ if (s->s_dev == dev) {
+ s->s_count++;
+ return s;
+ }
+ }
+ return NULL;
+}
+
+void drop_super(struct super_block *sb)
+{
+ up_read(&sb->s_umount);
+ __put_super(sb);
+}
+
+static void put_super(struct super_block *sb)
+{
+ up_write(&sb->s_umount);
+ __put_super(sb);
+}
+
+static inline void write_super(struct super_block *sb)
+{
+ lock_super(sb);
+ if (sb->s_root && sb->s_dirt)
+ if (sb->s_op && sb->s_op->write_super)
+ sb->s_op->write_super(sb);
+ unlock_super(sb);
+}

/*
* Note: check the dirty flag before waiting, so we don't
@@ -655,21 +691,29 @@
{
struct super_block * sb;

- for (sb = sb_entry(super_blocks.next);
- sb != sb_entry(&super_blocks);
- sb = sb_entry(sb->s_list.next)) {
- if (!sb->s_dev)
- continue;
- if (dev && sb->s_dev != dev)
- continue;
- if (!sb->s_dirt)
- continue;
- lock_super(sb);
- if (sb->s_dev && sb->s_dirt && (!dev || dev == sb->s_dev))
- if (sb->s_op && sb->s_op->write_super)
- sb->s_op->write_super(sb);
- unlock_super(sb);
+ if (dev) {
+ sb = get_super(dev);
+ if (sb) {
+ if (sb->s_dirt)
+ write_super(sb);
+ drop_super(sb);
+ }
+ return;
}
+restart:
+ spin_lock(&sb_lock);
+ sb = sb_entry(super_blocks.next);
+ while (sb != sb_entry(&super_blocks))
+ if (sb->s_dirt) {
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_read(&sb->s_umount);
+ write_super(sb);
+ drop_super(sb);
+ goto restart;
+ } else
+ sb = sb_entry(sb->s_list.next);
+ spin_unlock(&sb_lock);
}

/**
@@ -687,17 +731,21 @@
if (!dev)
return NULL;
restart:
- s = sb_entry(super_blocks.next);
- while (s != sb_entry(&super_blocks))
- if (s->s_dev == dev) {
- /* Yes, it sucks. As soon as we get refcounting... */
- lock_super(s);
- unlock_super(s);
- if (s->s_dev == dev)
- return s;
- goto restart;
- } else
- s = sb_entry(s->s_list.next);
+ spin_lock(&sb_lock);
+ s = find_super(dev);
+ if (s) {
+ spin_unlock(&sb_lock);
+ /* Yes, it sucks. As soon as we get refcounting... */
+ /* Almost there - next two lines will go away RSN */
+ lock_super(s);
+ unlock_super(s);
+ down_read(&s->s_umount);
+ if (s->s_root)
+ return s;
+ drop_super(s);
+ goto restart;
+ }
+ spin_unlock(&sb_lock);
return NULL;
}

@@ -714,6 +762,7 @@
if (s == NULL)
goto out;
err = vfs_statfs(s, &sbuf);
+ drop_super(s);
if (err)
goto out;

@@ -735,35 +784,23 @@
* the request.
*/

-static struct super_block *get_empty_super(void)
+static struct super_block *alloc_super(void)
{
- struct super_block *s;
-
- for (s = sb_entry(super_blocks.next);
- s != sb_entry(&super_blocks);
- s = sb_entry(s->s_list.next)) {
- if (s->s_dev)
- continue;
- return s;
- }
- /* Need a new one... */
- if (nr_super_blocks >= max_super_blocks)
- return NULL;
- s = kmalloc(sizeof(struct super_block), GFP_USER);
+ struct super_block *s = kmalloc(sizeof(struct super_block), GFP_USER);
if (s) {
- nr_super_blocks++;
memset(s, 0, sizeof(struct super_block));
INIT_LIST_HEAD(&s->s_dirty);
INIT_LIST_HEAD(&s->s_locked_inodes);
- list_add (&s->s_list, super_blocks.prev);
INIT_LIST_HEAD(&s->s_files);
- INIT_LIST_HEAD(&s->s_mounts);
init_rwsem(&s->s_umount);
sema_init(&s->s_lock, 1);
+ s->s_count = 1;
+ atomic_set(&s->s_active, 1);
sema_init(&s->s_vfs_rename_sem,1);
sema_init(&s->s_nfsd_free_path_sem,1);
sema_init(&s->s_dquot.dqio_sem, 1);
sema_init(&s->s_dquot.dqoff_sem, 1);
+ s->s_maxbytes = MAX_NON_LFS;
}
return s;
}
@@ -773,16 +810,16 @@
void *data, int silent)
{
struct super_block * s;
- s = get_empty_super();
+ s = alloc_super();
if (!s)
goto out;
s->s_dev = dev;
s->s_bdev = bdev;
s->s_flags = flags;
- s->s_dirt = 0;
s->s_type = type;
- s->s_dquot.flags = 0;
- s->s_maxbytes = MAX_NON_LFS;
+ spin_lock(&sb_lock);
+ list_add (&s->s_list, super_blocks.prev);
+ spin_unlock(&sb_lock);
lock_super(s);
if (!type->read_super(s, data, silent))
goto out_fail;
@@ -798,6 +835,11 @@
s->s_bdev = 0;
s->s_type = NULL;
unlock_super(s);
+ atomic_dec(&s->s_active);
+ spin_lock(&sb_lock);
+ list_del(&s->s_list);
+ spin_unlock(&sb_lock);
+ __put_super(s);
return NULL;
}

@@ -863,9 +905,25 @@
if (sb) {
if (fs_type == sb->s_type &&
((flags ^ sb->s_flags) & MS_RDONLY) == 0) {
+/*
+ * We are heavily relying on mount_sem here. We _will_ get rid of that
+ * ugliness RSN (and then atomicity of ->s_active will play), but first
+ * we need to get rid of "reuse" branch of get_empty_super() and that
+ * requires reference counters. Chicken and egg problem, but fortunately
+ * we can use the fact that right now all accesses to ->s_active are
+ * under mount_sem.
+ */
+ if (atomic_read(&sb->s_active)) {
+ spin_lock(&sb_lock);
+ sb->s_count--;
+ spin_unlock(&sb_lock);
+ }
+ atomic_inc(&sb->s_active);
+ up_read(&sb->s_umount);
path_release(&nd);
return sb;
}
+ drop_super(sb);
} else {
mode_t mode = FMODE_READ; /* we always need it ;-) */
if (!(flags & MS_RDONLY))
@@ -926,6 +984,7 @@
sb = fs_type->kern_mnt->mnt_sb;
if (!sb)
BUG();
+ atomic_inc(&sb->s_active);
do_remount_sb(sb, flags, data);
return sb;
}
@@ -938,12 +997,8 @@
struct file_system_type *fs = sb->s_type;
struct super_operations *sop = sb->s_op;

- spin_lock(&dcache_lock);
- if (!list_empty(&sb->s_mounts)) {
- spin_unlock(&dcache_lock);
+ if (!atomic_dec_and_test(&sb->s_active))
return;
- }
- spin_unlock(&dcache_lock);
down_write(&sb->s_umount);
lock_kernel();
sb->s_root = NULL;
@@ -975,12 +1030,15 @@
sb->s_type = NULL;
unlock_super(sb);
unlock_kernel();
- up_write(&sb->s_umount);
if (bdev) {
blkdev_put(bdev, BDEV_FS);
bdput(bdev);
} else
put_unnamed_dev(dev);
+ spin_lock(&sb_lock);
+ list_del(&sb->s_list);
+ spin_unlock(&sb_lock);
+ put_super(sb);
}

/*
@@ -1045,9 +1103,6 @@
mnt->mnt_root = dget(sb->s_root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
- spin_lock(&dcache_lock);
- list_add(&mnt->mnt_instances, &sb->s_mounts);
- spin_unlock(&dcache_lock);
type->kern_mnt = mnt;
return mnt;
}
@@ -1092,7 +1147,7 @@

spin_lock(&dcache_lock);

- if (mnt->mnt_instances.next != mnt->mnt_instances.prev) {
+ if (atomic_read(&sb->s_active) > 1) {
if (atomic_read(&mnt->mnt_count) > 2) {
spin_unlock(&dcache_lock);
return -EBUSY;
@@ -1243,13 +1298,13 @@
return err;

err = -ENOMEM;
+ down(&mount_sem);
mnt = clone_mnt(old_nd.mnt, old_nd.dentry);
if (mnt) {
- down(&mount_sem);
err = graft_tree(mnt, nd);
- up(&mount_sem);
mntput(mnt);
}
+ up(&mount_sem);
path_release(&old_nd);
return err;
}
@@ -1324,9 +1379,6 @@
mnt->mnt_root = dget(sb->s_root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
- spin_lock(&dcache_lock);
- list_add(&mnt->mnt_instances, &sb->s_mounts);
- spin_unlock(&dcache_lock);

/* Something was mounted here while we slept */
while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
@@ -1583,7 +1635,10 @@
check_disk_change(ROOT_DEV);
sb = get_super(ROOT_DEV);
if (sb) {
+ /* FIXME */
fs_type = sb->s_type;
+ atomic_inc(&sb->s_active);
+ up_read(&sb->s_umount);
goto mount_it;
}

diff -urN S6-pre2/include/linux/fs.h S6-pre2-super/include/linux/fs.h
--- S6-pre2/include/linux/fs.h Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/include/linux/fs.h Mon Jun 11 23:55:03 2001
@@ -61,7 +61,6 @@
};
extern struct inodes_stat_t inodes_stat;

-extern int max_super_blocks, nr_super_blocks;
extern int leases_enable, dir_notify_enable, lease_break_time;

#define NR_FILE 8192 /* this can well be larger on a larger system */
@@ -662,6 +661,7 @@
#include <linux/usbdev_fs_sb.h>

extern struct list_head super_blocks;
+extern spinlock_t sb_lock;

#define sb_entry(list) list_entry((list), struct super_block, s_list)
struct super_block {
@@ -679,13 +679,14 @@
struct dentry *s_root;
struct rw_semaphore s_umount;
struct semaphore s_lock;
+ int s_count;
+ atomic_t s_active;

struct list_head s_dirty; /* dirty inodes */
struct list_head s_locked_inodes;/* inodes being synced */
struct list_head s_files;

struct block_device *s_bdev;
- struct list_head s_mounts; /* vfsmount(s) of this one */
struct quota_mount_options s_dquot; /* Diskquota specific options */

union {
@@ -1122,6 +1123,7 @@
extern void sync_dev(kdev_t);
extern int fsync_dev(kdev_t);
extern int fsync_super(struct super_block *);
+extern int fsync_no_super(kdev_t);
extern void sync_inodes_sb(struct super_block *);
extern int fsync_inode_buffers(struct inode *);
extern int osync_inode_buffers(struct inode *);
@@ -1319,12 +1321,12 @@

extern struct file_system_type *get_fs_type(const char *name);
extern struct super_block *get_super(kdev_t);
-extern void put_super(kdev_t);
+extern void drop_super(struct super_block *sb);
static inline int is_mounted(kdev_t dev)
{
struct super_block *sb = get_super(dev);
if (sb) {
- /* drop_super(sb); will go here */
+ drop_super(sb);
return 1;
}
return 0;
diff -urN S6-pre2/include/linux/mount.h S6-pre2-super/include/linux/mount.h
--- S6-pre2/include/linux/mount.h Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/include/linux/mount.h Mon Jun 11 23:55:02 2001
@@ -18,7 +18,6 @@
struct vfsmount *mnt_parent; /* fs we are mounted on */
struct dentry *mnt_mountpoint; /* dentry of mountpoint */
struct dentry *mnt_root; /* root of the mounted tree */
- struct list_head mnt_instances; /* other vfsmounts of the same fs */
struct super_block *mnt_sb; /* pointer to superblock */
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
diff -urN S6-pre2/include/linux/quotaops.h S6-pre2-super/include/linux/quotaops.h
--- S6-pre2/include/linux/quotaops.h Sun Jun 10 13:15:27 2001
+++ S6-pre2-super/include/linux/quotaops.h Mon Jun 11 23:55:03 2001
@@ -21,7 +21,6 @@
*/
extern void dquot_initialize(struct inode *inode, short type);
extern void dquot_drop(struct inode *inode);
-extern void invalidate_dquots(kdev_t dev, short type);
extern int quota_off(struct super_block *sb, short type);
extern int sync_dquots(kdev_t dev, short type);

diff -urN S6-pre2/kernel/ksyms.c S6-pre2-super/kernel/ksyms.c
--- S6-pre2/kernel/ksyms.c Fri Jun 8 18:29:03 2001
+++ S6-pre2-super/kernel/ksyms.c Mon Jun 11 23:55:03 2001
@@ -129,6 +129,7 @@
EXPORT_SYMBOL(update_atime);
EXPORT_SYMBOL(get_fs_type);
EXPORT_SYMBOL(get_super);
+EXPORT_SYMBOL(drop_super);
EXPORT_SYMBOL(getname);
EXPORT_SYMBOL(names_cachep);
EXPORT_SYMBOL(fput);
diff -urN S6-pre2/kernel/sysctl.c S6-pre2-super/kernel/sysctl.c
--- S6-pre2/kernel/sysctl.c Sat Apr 14 21:41:29 2001
+++ S6-pre2-super/kernel/sysctl.c Mon Jun 11 23:55:03 2001
@@ -286,10 +286,6 @@
0444, NULL, &proc_dointvec},
{FS_MAXFILE, "file-max", &files_stat.max_files, sizeof(int),
0644, NULL, &proc_dointvec},
- {FS_NRSUPER, "super-nr", &nr_super_blocks, sizeof(int),
- 0444, NULL, &proc_dointvec},
- {FS_MAXSUPER, "super-max", &max_super_blocks, sizeof(int),
- 0644, NULL, &proc_dointvec},
{FS_NRDQUOT, "dquot-nr", &nr_dquots, 2*sizeof(int),
0444, NULL, &proc_dointvec},
{FS_MAXDQUOT, "dquot-max", &max_dquots, sizeof(int),

-
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