fs: seq_file - add event counter to simplify poll() support

Moving the event counter into the dynamically allocated 'struc seq_file'
allows poll() support without the need to allocate its own tracking
structure.

All current users are switched over to use the new counter.

Requested-by: Andrew Morton akpm@linux-foundation.org
Acked-by: NeilBrown <neilb@suse.de>
Tested-by: Lucas De Marchi lucas.demarchi@profusion.mobi
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 91e31e2..dfc9425 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6394,16 +6394,11 @@ static void md_seq_stop(struct seq_file *seq, void *v)
                mddev_put(mddev);
 }
 
-struct mdstat_info {
-       int event;
-};
-
 static int md_seq_show(struct seq_file *seq, void *v)
 {
        mddev_t *mddev = v;
        sector_t sectors;
        mdk_rdev_t *rdev;
-       struct mdstat_info *mi = seq->private;
        struct bitmap *bitmap;
 
        if (v == (void*)1) {
@@ -6415,7 +6410,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
 
                spin_unlock(&pers_lock);
                seq_printf(seq, "\n");
-               mi->event = atomic_read(&md_event_count);
+               seq->poll_event = atomic_read(&md_event_count);
                return 0;
        }
        if (v == (void*)2) {
@@ -6527,26 +6522,21 @@ static const struct seq_operations md_seq_ops = {
 
 static int md_seq_open(struct inode *inode, struct file *file)
 {
+       struct seq_file *seq;
        int error;
-       struct mdstat_info *mi = kmalloc(sizeof(*mi), GFP_KERNEL);
-       if (mi == NULL)
-               return -ENOMEM;
 
        error = seq_open(file, &md_seq_ops);
        if (error)
-               kfree(mi);
-       else {
-               struct seq_file *p = file->private_data;
-               p->private = mi;
-               mi->event = atomic_read(&md_event_count);
-       }
+               return error;
+
+       seq = file->private_data;
+       seq->poll_event = atomic_read(&md_event_count);
        return error;
 }
 
 static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
 {
-       struct seq_file *m = filp->private_data;
-       struct mdstat_info *mi = m->private;
+       struct seq_file *seq = filp->private_data;
        int mask;
 
        poll_wait(filp, &md_event_waiters, wait);
@@ -6554,7 +6544,7 @@ static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
        /* always allow read */
        mask = POLLIN | POLLRDNORM;
 
-       if (mi->event != atomic_read(&md_event_count))
+       if (seq->poll_event != atomic_read(&md_event_count))
                mask |= POLLERR | POLLPRI;
        return mask;
 }

diff --git a/fs/namespace.c b/fs/namespace.c
index fe59bd1..cda50fe 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -934,8 +934,8 @@ int mnt_had_events(struct proc_mounts *p)
        int res = 0;
 
        br_read_lock(vfsmount_lock);
-       if (p->event != ns->event) {
-               p->event = ns->event;
+       if (p->m.poll_event != ns->event) {
+               p->m.poll_event = ns->event;
                res = 1;
        }
        br_read_unlock(vfsmount_lock);

diff --git a/fs/proc/base.c b/fs/proc/base.c
index be1ff93..3dc5e2a 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -673,7 +673,7 @@ static int mounts_open_common(struct inode *inode, struct file *file,
        p->m.private = p;
        p->ns = ns;
        p->root = root;
-       p->event = ns->event;
+       p->m.poll_event = ns->event;
 
        return 0;
 

diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h
index 0b89efc..2930485 100644 (file)
--- a/include/linux/mnt_namespace.h
+++ b/include/linux/mnt_namespace.h
@@ -18,7 +18,6 @@ struct proc_mounts {
        struct seq_file m; /* must be the first element */
        struct mnt_namespace *ns;
        struct path root;
-       int event;
 };
 
 struct fs_struct;

diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 03c0232..be720cd 100644 (file)
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -23,6 +23,7 @@ struct seq_file {
        u64 version;
        struct mutex lock;
        const struct seq_operations *op;
+       int poll_event;
        void *private;
 };
 

diff --git a/mm/swapfile.c b/mm/swapfile.c
index ff8dc1a..1b8c339 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1681,19 +1681,14 @@ out:
 }
 
 #ifdef CONFIG_PROC_FS
-struct proc_swaps {
-       struct seq_file seq;
-       int event;
-};
-
 static unsigned swaps_poll(struct file *file, poll_table *wait)
 {
-       struct proc_swaps *s = file->private_data;
+       struct seq_file *seq = file->private_data;
 
        poll_wait(file, &proc_poll_wait, wait);
 
-       if (s->event != atomic_read(&proc_poll_event)) {
-               s->event = atomic_read(&proc_poll_event);
+       if (seq->poll_event != atomic_read(&proc_poll_event)) {
+               seq->poll_event = atomic_read(&proc_poll_event);
                return POLLIN | POLLRDNORM | POLLERR | POLLPRI;
        }
 
@@ -1783,24 +1778,16 @@ static const struct seq_operations swaps_op = {
 
 static int swaps_open(struct inode *inode, struct file *file)
 {
-       struct proc_swaps *s;
+       struct seq_file *seq;
        int ret;
 
-       s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL);
-       if (!s)
-               return -ENOMEM;
-
-       file->private_data = s;
-
        ret = seq_open(file, &swaps_op);
-       if (ret) {
-               kfree(s);
+       if (ret)
                return ret;
-       }
 
-       s->seq.private = s;
-       s->event = atomic_read(&proc_poll_event);
-       return ret;
+       seq = file->private_data;
+       seq->poll_event = atomic_read(&proc_poll_event);
+       return 0;
 }
 
 static const struct file_operations proc_swaps_operations = {