[readdir] convert procfs

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

9 files changed, 284 insertions, 489 deletions

diff --git a/fs/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index cd3e389..fc90ab1 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -542,8 +542,8 @@ static const struct file_operations hppfs_file_fops = {
 };
 
 struct hppfs_dirent {
-	void *vfs_dirent;
-	filldir_t filldir;
+	struct dir_context ctx;
+	struct dir_context *caller;
 	struct dentry *dentry;
 };
 
@@ -555,34 +555,29 @@ static int hppfs_filldir(void *d, const char *name, int size,
 	if (file_removed(dirent->dentry, name))
 		return 0;
 
-	return (*dirent->filldir)(dirent->vfs_dirent, name, size, offset,
-				  inode, type);
+	dirent->caller->pos = dirent->ctx.pos;
+	return !dir_emit(dirent->caller, name, size, inode, type);
 }
 
-static int hppfs_readdir(struct file *file, void *ent, filldir_t filldir)
+static int hppfs_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct hppfs_private *data = file->private_data;
 	struct file *proc_file = data->proc_file;
-	int (*readdir)(struct file *, void *, filldir_t);
-	struct hppfs_dirent dirent = ((struct hppfs_dirent)
-		                      { .vfs_dirent  	= ent,
-					.filldir 	= filldir,
-					.dentry  	= file->f_path.dentry
-				      });
+	struct hppfs_dirent d = {
+		.ctx.actor	= hppfs_filldir,
+		.caller		= ctx,
+		.dentry  	= file->f_path.dentry
+	};
 	int err;
-
-	readdir = file_inode(proc_file)->i_fop->readdir;
-
-	proc_file->f_pos = file->f_pos;
-	err = (*readdir)(proc_file, &dirent, hppfs_filldir);
-	file->f_pos = proc_file->f_pos;
-
+	proc_file->f_pos = ctx->pos;
+	err = iterate_dir(proc_file, &d.ctx);
+	ctx->pos = d.ctx.pos;
 	return err;
 }
 
 static const struct file_operations hppfs_dir_fops = {
 	.owner		= NULL,
-	.readdir	= hppfs_readdir,
+	.iterate	= hppfs_readdir,
 	.open		= hppfs_dir_open,
 	.llseek		= default_llseek,
 	.release	= hppfs_release,
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c3834da..0016350 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1681,11 +1681,11 @@ const struct dentry_operations pid_dentry_operations =
  * reported by readdir in sync with the inode numbers reported
  * by stat.
  */
-int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
+bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 	const char *name, int len,
 	instantiate_t instantiate, struct task_struct *task, const void *ptr)
 {
-	struct dentry *child, *dir = filp->f_path.dentry;
+	struct dentry *child, *dir = file->f_path.dentry;
 	struct inode *inode;
 	struct qstr qname;
 	ino_t ino = 0;
@@ -1720,7 +1720,7 @@ end_instantiate:
 		ino = find_inode_number(dir, &qname);
 	if (!ino)
 		ino = 1;
-	return filldir(dirent, name, len, filp->f_pos, ino, type);
+	return dir_emit(ctx, name, len, ino, type);
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1931,14 +1931,15 @@ static const struct inode_operations proc_map_files_inode_operations = {
 };
 
 static int
-proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
+proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
 	struct vm_area_struct *vma;
 	struct task_struct *task;
 	struct mm_struct *mm;
-	ino_t ino;
+	unsigned long nr_files, pos, i;
+	struct flex_array *fa = NULL;
+	struct map_files_info info;
+	struct map_files_info *p;
 	int ret;
 
 	ret = -EPERM;
@@ -1946,7 +1947,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		goto out;
 
 	ret = -ENOENT;
-	task = get_proc_task(inode);
+	task = get_proc_task(file_inode(file));
 	if (!task)
 		goto out;
 
@@ -1955,91 +1956,73 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		goto out_put_task;
 
 	ret = 0;
-	switch (filp->f_pos) {
-	case 0:
-		ino = inode->i_ino;
-		if (filldir(dirent, ".", 1, 0, ino, DT_DIR) < 0)
-			goto out_put_task;
-		filp->f_pos++;
-	case 1:
-		ino = parent_ino(dentry);
-		if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
-			goto out_put_task;
-		filp->f_pos++;
-	default:
-	{
-		unsigned long nr_files, pos, i;
-		struct flex_array *fa = NULL;
-		struct map_files_info info;
-		struct map_files_info *p;
-
-		mm = get_task_mm(task);
-		if (!mm)
-			goto out_put_task;
-		down_read(&mm->mmap_sem);
+	if (!dir_emit_dots(file, ctx))
+		goto out_put_task;
 
-		nr_files = 0;
+	mm = get_task_mm(task);
+	if (!mm)
+		goto out_put_task;
+	down_read(&mm->mmap_sem);
 
-		/*
-		 * We need two passes here:
-		 *
-		 *  1) Collect vmas of mapped files with mmap_sem taken
-		 *  2) Release mmap_sem and instantiate entries
-		 *
-		 * otherwise we get lockdep complained, since filldir()
-		 * routine might require mmap_sem taken in might_fault().
-		 */
+	nr_files = 0;
 
-		for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
-			if (vma->vm_file && ++pos > filp->f_pos)
-				nr_files++;
-		}
+	/*
+	 * We need two passes here:
+	 *
+	 *  1) Collect vmas of mapped files with mmap_sem taken
+	 *  2) Release mmap_sem and instantiate entries
+	 *
+	 * otherwise we get lockdep complained, since filldir()
+	 * routine might require mmap_sem taken in might_fault().
+	 */
 
-		if (nr_files) {
-			fa = flex_array_alloc(sizeof(info), nr_files,
-						GFP_KERNEL);
-			if (!fa || flex_array_prealloc(fa, 0, nr_files,
-							GFP_KERNEL)) {
-				ret = -ENOMEM;
-				if (fa)
-					flex_array_free(fa);
-				up_read(&mm->mmap_sem);
-				mmput(mm);
-				goto out_put_task;
-			}
-			for (i = 0, vma = mm->mmap, pos = 2; vma;
-					vma = vma->vm_next) {
-				if (!vma->vm_file)
-					continue;
-				if (++pos <= filp->f_pos)
-					continue;
-
-				info.mode = vma->vm_file->f_mode;
-				info.len = snprintf(info.name,
-						sizeof(info.name), "%lx-%lx",
-						vma->vm_start, vma->vm_end);
-				if (flex_array_put(fa, i++, &info, GFP_KERNEL))
-					BUG();
-			}
+	for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
+		if (vma->vm_file && ++pos > ctx->pos)
+			nr_files++;
+	}
+
+	if (nr_files) {
+		fa = flex_array_alloc(sizeof(info), nr_files,
+					GFP_KERNEL);
+		if (!fa || flex_array_prealloc(fa, 0, nr_files,
+						GFP_KERNEL)) {
+			ret = -ENOMEM;
+			if (fa)
+				flex_array_free(fa);
+			up_read(&mm->mmap_sem);
+			mmput(mm);
+			goto out_put_task;
 		}
-		up_read(&mm->mmap_sem);
-
-		for (i = 0; i < nr_files; i++) {
-			p = flex_array_get(fa, i);
-			ret = proc_fill_cache(filp, dirent, filldir,
-					      p->name, p->len,
-					      proc_map_files_instantiate,
-					      task,
-					      (void *)(unsigned long)p->mode);
-			if (ret)
-				break;
-			filp->f_pos++;
+		for (i = 0, vma = mm->mmap, pos = 2; vma;
+				vma = vma->vm_next) {
+			if (!vma->vm_file)
+				continue;
+			if (++pos <= ctx->pos)
+				continue;
+
+			info.mode = vma->vm_file->f_mode;
+			info.len = snprintf(info.name,
+					sizeof(info.name), "%lx-%lx",
+					vma->vm_start, vma->vm_end);
+			if (flex_array_put(fa, i++, &info, GFP_KERNEL))
+				BUG();
 		}
-		if (fa)
-			flex_array_free(fa);
-		mmput(mm);
 	}
+	up_read(&mm->mmap_sem);
+
+	for (i = 0; i < nr_files; i++) {
+		p = flex_array_get(fa, i);
+		if (!proc_fill_cache(file, ctx,
+				      p->name, p->len,
+				      proc_map_files_instantiate,
+				      task,
+				      (void *)(unsigned long)p->mode))
+			break;
+		ctx->pos++;
 	}
+	if (fa)
+		flex_array_free(fa);
+	mmput(mm);
 
 out_put_task:
 	put_task_struct(task);
@@ -2049,7 +2032,7 @@ out:
 
 static const struct file_operations proc_map_files_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_map_files_readdir,
+	.iterate	= proc_map_files_readdir,
 	.llseek		= default_llseek,
 };
 
@@ -2217,67 +2200,30 @@ out_no_task:
 	return error;
 }
 
-static int proc_pident_fill_cache(struct file *filp, void *dirent,
-	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
-{
-	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
-				proc_pident_instantiate, task, p);
-}
-
-static int proc_pident_readdir(struct file *filp,
-		void *dirent, filldir_t filldir,
+static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
 		const struct pid_entry *ents, unsigned int nents)
 {
-	int i;
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
-	struct task_struct *task = get_proc_task(inode);
-	const struct pid_entry *p, *last;
-	ino_t ino;
-	int ret;
+	struct task_struct *task = get_proc_task(file_inode(file));
+	const struct pid_entry *p;
 
-	ret = -ENOENT;
 	if (!task)
-		goto out_no_task;
+		return -ENOENT;
 
-	ret = 0;
-	i = filp->f_pos;
-	switch (i) {
-	case 0:
-		ino = inode->i_ino;
-		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
-			goto out;
-		i++;
-		filp->f_pos++;
-		/* fall through */
-	case 1:
-		ino = parent_ino(dentry);
-		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
-			goto out;
-		i++;
-		filp->f_pos++;
-		/* fall through */
-	default:
-		i -= 2;
-		if (i >= nents) {
-			ret = 1;
-			goto out;
-		}
-		p = ents + i;
-		last = &ents[nents - 1];
-		while (p <= last) {
-			if (proc_pident_fill_cache(filp, dirent, filldir, task, p) < 0)
-				goto out;
-			filp->f_pos++;
-			p++;
-		}
-	}
+	if (!dir_emit_dots(file, ctx))
+		goto out;
+
+	if (ctx->pos >= nents + 2)
+		goto out;
 
-	ret = 1;
+	for (p = ents + (ctx->pos - 2); p <= ents + nents - 1; p++) {
+		if (!proc_fill_cache(file, ctx, p->name, p->len,
+				proc_pident_instantiate, task, p))
+			break;
+		ctx->pos++;
+	}
 out:
 	put_task_struct(task);
-out_no_task:
-	return ret;
+	return 0;
 }
 
 #ifdef CONFIG_SECURITY
@@ -2362,16 +2308,15 @@ static const struct pid_entry attr_dir_stuff[] = {
 	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
 };
 
-static int proc_attr_dir_readdir(struct file * filp,
-			     void * dirent, filldir_t filldir)
+static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
 {
-	return proc_pident_readdir(filp,dirent,filldir,
-				   attr_dir_stuff,ARRAY_SIZE(attr_dir_stuff));
+	return proc_pident_readdir(file, ctx, 
+				   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
 }
 
 static const struct file_operations proc_attr_dir_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_attr_dir_readdir,
+	.iterate	= proc_attr_dir_readdir,
 	.llseek		= default_llseek,
 };
 
@@ -2725,16 +2670,15 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
 };
 
-static int proc_tgid_base_readdir(struct file * filp,
-			     void * dirent, filldir_t filldir)
+static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
 {
-	return proc_pident_readdir(filp,dirent,filldir,
-				   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
+	return proc_pident_readdir(file, ctx,
+				   tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
 }
 
 static const struct file_operations proc_tgid_base_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_tgid_base_readdir,
+	.iterate	= proc_tgid_base_readdir,
 	.llseek		= default_llseek,
 };
 
@@ -2936,58 +2880,42 @@ retry:
 
 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 1)
 
-static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
-	struct tgid_iter iter)
-{
-	char name[PROC_NUMBUF];
-	int len = snprintf(name, sizeof(name), "%d", iter.tgid);
-	return proc_fill_cache(filp, dirent, filldir, name, len,
-				proc_pid_instantiate, iter.task, NULL);
-}
-
-static int fake_filldir(void *buf, const char *name, int namelen,
-			loff_t offset, u64 ino, unsigned d_type)
-{
-	return 0;
-}
-
 /* for the /proc/ directory itself, after non-process stuff has been done */
-int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
+int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct tgid_iter iter;
 	struct pid_namespace *ns;
-	filldir_t __filldir;
-	loff_t pos = filp->f_pos;
+	loff_t pos = ctx->pos;
 
 	if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
-		goto out;
+		return 0;
 
 	if (pos == TGID_OFFSET - 1) {
-		if (proc_fill_cache(filp, dirent, filldir, "self", 4,
-					NULL, NULL, NULL) < 0)
-			goto out;
+		if (!proc_fill_cache(file, ctx, "self", 4, NULL, NULL, NULL))
+			return 0;
 		iter.tgid = 0;
 	} else {
 		iter.tgid = pos - TGID_OFFSET;
 	}
 	iter.task = NULL;
-	ns = filp->f_dentry->d_sb->s_fs_info;
+	ns = file->f_dentry->d_sb->s_fs_info;
 	for (iter = next_tgid(ns, iter);
 	     iter.task;
 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
-		if (has_pid_permissions(ns, iter.task, 2))
-			__filldir = filldir;
-		else
-			__filldir = fake_filldir;
+		char name[PROC_NUMBUF];
+		int len;
+		if (!has_pid_permissions(ns, iter.task, 2))
+			continue;
 
-		filp->f_pos = iter.tgid + TGID_OFFSET;
-		if (proc_pid_fill_cache(filp, dirent, __filldir, iter) < 0) {
+		len = snprintf(name, sizeof(name), "%d", iter.tgid);
+		ctx->pos = iter.tgid + TGID_OFFSET;
+		if (!proc_fill_cache(file, ctx, name, len,
+				     proc_pid_instantiate, iter.task, NULL)) {
 			put_task_struct(iter.task);
-			goto out;
+			return 0;
 		}
 	}
-	filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
-out:
+	ctx->pos = PID_MAX_LIMIT + TGID_OFFSET;
 	return 0;
 }
 
@@ -3075,11 +3003,10 @@ static const struct pid_entry tid_base_stuff[] = {
 #endif
 };
 
-static int proc_tid_base_readdir(struct file * filp,
-			     void * dirent, filldir_t filldir)
+static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
 {
-	return proc_pident_readdir(filp,dirent,filldir,
-				   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
+	return proc_pident_readdir(file, ctx,
+				   tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
 }
 
 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
@@ -3090,7 +3017,7 @@ static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *den
 
 static const struct file_operations proc_tid_base_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_tid_base_readdir,
+	.iterate	= proc_tid_base_readdir,
 	.llseek		= default_llseek,
 };
 
@@ -3231,30 +3158,16 @@ static struct task_struct *next_tid(struct task_struct *start)
 	return pos;
 }
 
-static int proc_task_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
-	struct task_struct *task, int tid)
-{
-	char name[PROC_NUMBUF];
-	int len = snprintf(name, sizeof(name), "%d", tid);
-	return proc_fill_cache(filp, dirent, filldir, name, len,
-				proc_task_instantiate, task, NULL);
-}
-
 /* for the /proc/TGID/task/ directories */
-static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
+static int proc_task_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
 	struct task_struct *leader = NULL;
-	struct task_struct *task;
-	int retval = -ENOENT;
-	ino_t ino;
-	int tid;
+	struct task_struct *task = get_proc_task(file_inode(file));
 	struct pid_namespace *ns;
+	int tid;
 
-	task = get_proc_task(inode);
 	if (!task)
-		goto out_no_task;
+		return -ENOENT;
 	rcu_read_lock();
 	if (pid_alive(task)) {
 		leader = task->group_leader;
@@ -3263,46 +3176,36 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
 	rcu_read_unlock();
 	put_task_struct(task);
 	if (!leader)
-		goto out_no_task;
-	retval = 0;
+		return -ENOENT;
 
-	switch ((unsigned long)filp->f_pos) {
-	case 0:
-		ino = inode->i_ino;
-		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) < 0)
-			goto out;
-		filp->f_pos++;
-		/* fall through */
-	case 1:
-		ino = parent_ino(dentry);
-		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) < 0)
-			goto out;
-		filp->f_pos++;
-		/* fall through */
-	}
+	if (!dir_emit_dots(file, ctx))
+		goto out;
 
 	/* f_version caches the tgid value that the last readdir call couldn't
 	 * return. lseek aka telldir automagically resets f_version to 0.
 	 */
-	ns = filp->f_dentry->d_sb->s_fs_info;
-	tid = (int)filp->f_version;
-	filp->f_version = 0;
-	for (task = first_tid(leader, tid, filp->f_pos - 2, ns);
+	ns = file->f_dentry->d_sb->s_fs_info;
+	tid = (int)file->f_version;
+	file->f_version = 0;
+	for (task = first_tid(leader, tid, ctx->pos - 2, ns);
 	     task;
-	     task = next_tid(task), filp->f_pos++) {
+	     task = next_tid(task), ctx->pos++) {
+		char name[PROC_NUMBUF];
+		int len;
 		tid = task_pid_nr_ns(task, ns);
-		if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
+		len = snprintf(name, sizeof(name), "%d", tid);
+		if (!proc_fill_cache(file, ctx, name, len,
+				proc_task_instantiate, task, NULL)) {
 			/* returning this tgid failed, save it as the first
 			 * pid for the next readir call */
-			filp->f_version = (u64)tid;
+			file->f_version = (u64)tid;
 			put_task_struct(task);
 			break;
 		}
 	}
 out:
 	put_task_struct(leader);
-out_no_task:
-	return retval;
+	return 0;
 }
 
 static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
@@ -3328,6 +3231,6 @@ static const struct inode_operations proc_task_inode_operations = {
 
 static const struct file_operations proc_task_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_task_readdir,
+	.iterate	= proc_task_readdir,
 	.llseek		= default_llseek,
 };
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index d7a4a28..1441f14 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -219,74 +219,58 @@ out_no_task:
 	return result;
 }
 
-static int proc_readfd_common(struct file * filp, void * dirent,
-			      filldir_t filldir, instantiate_t instantiate)
+static int proc_readfd_common(struct file *file, struct dir_context *ctx,
+			      instantiate_t instantiate)
 {
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
-	struct task_struct *p = get_proc_task(inode);
+	struct task_struct *p = get_proc_task(file_inode(file));
 	struct files_struct *files;
-	unsigned int fd, ino;
-	int retval;
+	unsigned int fd;
 
-	retval = -ENOENT;
 	if (!p)
-		goto out_no_task;
-	retval = 0;
-
-	fd = filp->f_pos;
-	switch (fd) {
-		case 0:
-			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
-				goto out;
-			filp->f_pos++;
-		case 1:
-			ino = parent_ino(dentry);
-			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
-				goto out;
-			filp->f_pos++;
-		default:
-			files = get_files_struct(p);
-			if (!files)
-				goto out;
-			rcu_read_lock();
-			for (fd = filp->f_pos - 2;
-			     fd < files_fdtable(files)->max_fds;
-			     fd++, filp->f_pos++) {
-				char name[PROC_NUMBUF];
-				int len;
-				int rv;
-
-				if (!fcheck_files(files, fd))
-					continue;
-				rcu_read_unlock();
+		return -ENOENT;
 
-				len = snprintf(name, sizeof(name), "%d", fd);
-				rv = proc_fill_cache(filp, dirent, filldir,
-						     name, len, instantiate, p,
-						     (void *)(unsigned long)fd);
-				if (rv < 0)
-					goto out_fd_loop;
-				rcu_read_lock();
-			}
-			rcu_read_unlock();
-out_fd_loop:
-			put_files_struct(files);
+	if (!dir_emit_dots(file, ctx))
+		goto out;
+	if (!dir_emit_dots(file, ctx))
+		goto out;
+	files = get_files_struct(p);
+	if (!files)
+		goto out;
+
+	rcu_read_lock();
+	for (fd = ctx->pos - 2;
+	     fd < files_fdtable(files)->max_fds;
+	     fd++, ctx->pos++) {
+		char name[PROC_NUMBUF];
+		int len;
+
+		if (!fcheck_files(files, fd))
+			continue;
+		rcu_read_unlock();
+
+		len = snprintf(name, sizeof(name), "%d", fd);
+		if (!proc_fill_cache(file, ctx,
+				     name, len, instantiate, p,
+				     (void *)(unsigned long)fd))
+			goto out_fd_loop;
+		rcu_read_lock();
 	}
+	rcu_read_unlock();
+out_fd_loop:
+	put_files_struct(files);
 out:
 	put_task_struct(p);
-out_no_task:
-	return retval;
+	return 0;
 }
 
-static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
+static int proc_readfd(struct file *file, struct dir_context *ctx)
 {
-	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
+	return proc_readfd_common(file, ctx, proc_fd_instantiate);
 }
 
 const struct file_operations proc_fd_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_readfd,
+	.iterate	= proc_readfd,
 	.llseek		= default_llseek,
 };
 
@@ -351,9 +335,9 @@ proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
 	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
 }
 
-static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
+static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
 {
-	return proc_readfd_common(filp, dirent, filldir,
+	return proc_readfd_common(file, ctx,
 				  proc_fdinfo_instantiate);
 }
 
@@ -364,6 +348,6 @@ const struct inode_operations proc_fdinfo_inode_operations = {
 
 const struct file_operations proc_fdinfo_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_readfdinfo,
+	.iterate	= proc_readfdinfo,
 	.llseek		= default_llseek,
 };
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index a2596af..94441a4 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -233,76 +233,52 @@ struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
  * value of the readdir() call, as long as it's non-negative
  * for success..
  */
-int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
-		filldir_t filldir)
+int proc_readdir_de(struct proc_dir_entry *de, struct file *file,
+		    struct dir_context *ctx)
 {
-	unsigned int ino;
 	int i;
-	struct inode *inode = file_inode(filp);
-	int ret = 0;
-
-	ino = inode->i_ino;
-	i = filp->f_pos;
-	switch (i) {
-		case 0:
-			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
-				goto out;
-			i++;
-			filp->f_pos++;
-			/* fall through */
-		case 1:
-			if (filldir(dirent, "..", 2, i,
-				    parent_ino(filp->f_path.dentry),
-				    DT_DIR) < 0)
-				goto out;
-			i++;
-			filp->f_pos++;
-			/* fall through */
-		default:
-			spin_lock(&proc_subdir_lock);
-			de = de->subdir;
-			i -= 2;
-			for (;;) {
-				if (!de) {
-					ret = 1;
-					spin_unlock(&proc_subdir_lock);
-					goto out;
-				}
-				if (!i)
-					break;
-				de = de->next;
-				i--;
-			}
 
-			do {
-				struct proc_dir_entry *next;
-
-				/* filldir passes info to user space */
-				pde_get(de);
-				spin_unlock(&proc_subdir_lock);
-				if (filldir(dirent, de->name, de->namelen, filp->f_pos,
-					    de->low_ino, de->mode >> 12) < 0) {
-					pde_put(de);
-					goto out;
-				}
-				spin_lock(&proc_subdir_lock);
-				filp->f_pos++;
-				next = de->next;
-				pde_put(de);
-				de = next;
-			} while (de);
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	spin_lock(&proc_subdir_lock);
+	de = de->subdir;
+	i = ctx->pos - 2;
+	for (;;) {
+		if (!de) {
 			spin_unlock(&proc_subdir_lock);
+			return 0;
+		}
+		if (!i)
+			break;
+		de = de->next;
+		i--;
 	}
-	ret = 1;
-out:
-	return ret;	
+
+	do {
+		struct proc_dir_entry *next;
+		pde_get(de);
+		spin_unlock(&proc_subdir_lock);
+		if (!dir_emit(ctx, de->name, de->namelen,
+			    de->low_ino, de->mode >> 12)) {
+			pde_put(de);
+			return 0;
+		}
+		spin_lock(&proc_subdir_lock);
+		ctx->pos++;
+		next = de->next;
+		pde_put(de);
+		de = next;
+	} while (de);
+	spin_unlock(&proc_subdir_lock);
+	return 0;
 }
 
-int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
+int proc_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct inode *inode = file_inode(filp);
+	struct inode *inode = file_inode(file);
 
-	return proc_readdir_de(PDE(inode), filp, dirent, filldir);
+	return proc_readdir_de(PDE(inode), file, ctx);
 }
 
 /*
@@ -313,7 +289,7 @@ int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
 static const struct file_operations proc_dir_operations = {
 	.llseek			= generic_file_llseek,
 	.read			= generic_read_dir,
-	.readdir		= proc_readdir,
+	.iterate		= proc_readdir,
 };
 
 /*
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index d600fb0..4eae2e1 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -165,14 +165,14 @@ extern int proc_setattr(struct dentry *, struct iattr *);
 extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *);
 extern int pid_revalidate(struct dentry *, unsigned int);
 extern int pid_delete_dentry(const struct dentry *);
-extern int proc_pid_readdir(struct file *, void *, filldir_t);
+extern int proc_pid_readdir(struct file *, struct dir_context *);
 extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int);
 extern loff_t mem_lseek(struct file *, loff_t, int);
 
 /* Lookups */
 typedef struct dentry *instantiate_t(struct inode *, struct dentry *,
 				     struct task_struct *, const void *);
-extern int proc_fill_cache(struct file *, void *, filldir_t, const char *, int,
+extern bool proc_fill_cache(struct file *, struct dir_context *, const char *, int,
 			   instantiate_t, struct task_struct *, const void *);
 
 /*
@@ -183,8 +183,8 @@ extern spinlock_t proc_subdir_lock;
 extern struct dentry *proc_lookup(struct inode *, struct dentry *, unsigned int);
 extern struct dentry *proc_lookup_de(struct proc_dir_entry *, struct inode *,
 				     struct dentry *);
-extern int proc_readdir(struct file *, void *, filldir_t);
-extern int proc_readdir_de(struct proc_dir_entry *, struct file *, void *, filldir_t);
+extern int proc_readdir(struct file *, struct dir_context *);
+extern int proc_readdir_de(struct proc_dir_entry *, struct file *, struct dir_context *);
 
 static inline struct proc_dir_entry *pde_get(struct proc_dir_entry *pde)
 {
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 54bdc67..f6abbbb 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -213,74 +213,36 @@ out:
 	return error;
 }
 
-static int proc_ns_fill_cache(struct file *filp, void *dirent,
-	filldir_t filldir, struct task_struct *task,
-	const struct proc_ns_operations *ops)
+static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 {
-	return proc_fill_cache(filp, dirent, filldir,
-				ops->name, strlen(ops->name),
-				proc_ns_instantiate, task, ops);
-}
-
-static int proc_ns_dir_readdir(struct file *filp, void *dirent,
-				filldir_t filldir)
-{
-	int i;
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
-	struct task_struct *task = get_proc_task(inode);
+	struct task_struct *task = get_proc_task(file_inode(file));
 	const struct proc_ns_operations **entry, **last;
-	ino_t ino;
-	int ret;
 
-	ret = -ENOENT;
 	if (!task)
-		goto out_no_task;
+		return -ENOENT;
 
-	ret = 0;
-	i = filp->f_pos;
-	switch (i) {
-	case 0:
-		ino = inode->i_ino;
-		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
-			goto out;
-		i++;
-		filp->f_pos++;
-		/* fall through */
-	case 1:
-		ino = parent_ino(dentry);
-		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
-			goto out;
-		i++;
-		filp->f_pos++;
-		/* fall through */
-	default:
-		i -= 2;
-		if (i >= ARRAY_SIZE(ns_entries)) {
-			ret = 1;
-			goto out;
-		}
-		entry = ns_entries + i;
-		last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
-		while (entry <= last) {
-			if (proc_ns_fill_cache(filp, dirent, filldir,
-						task, *entry) < 0)
-				goto out;
-			filp->f_pos++;
-			entry++;
-		}
+	if (!dir_emit_dots(file, ctx))
+		goto out;
+	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
+		goto out;
+	entry = ns_entries + (ctx->pos - 2);
+	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
+	while (entry <= last) {
+		const struct proc_ns_operations *ops = *entry;
+		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
+				     proc_ns_instantiate, task, ops))
+			break;
+		ctx->pos++;
+		entry++;
 	}
-
-	ret = 1;
 out:
 	put_task_struct(task);
-out_no_task:
-	return ret;
+	return 0;
 }
 
 const struct file_operations proc_ns_dir_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_ns_dir_readdir,
+	.iterate	= proc_ns_dir_readdir,
 };
 
 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 986e832..4677bb7 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -160,16 +160,15 @@ const struct inode_operations proc_net_inode_operations = {
 	.getattr	= proc_tgid_net_getattr,
 };
 
-static int proc_tgid_net_readdir(struct file *filp, void *dirent,
-		filldir_t filldir)
+static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
 {
 	int ret;
 	struct net *net;
 
 	ret = -EINVAL;
-	net = get_proc_task_net(file_inode(filp));
+	net = get_proc_task_net(file_inode(file));
 	if (net != NULL) {
-		ret = proc_readdir_de(net->proc_net, filp, dirent, filldir);
+		ret = proc_readdir_de(net->proc_net, file, ctx);
 		put_net(net);
 	}
 	return ret;
@@ -178,7 +177,7 @@ static int proc_tgid_net_readdir(struct file *filp, void *dirent,
 const struct file_operations proc_net_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
-	.readdir	= proc_tgid_net_readdir,
+	.iterate	= proc_tgid_net_readdir,
 };
 
 static __net_init int proc_net_ns_init(struct net *net)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index ac05f33..f3a570e 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -573,12 +573,12 @@ out:
 	return ret;
 }
 
-static int proc_sys_fill_cache(struct file *filp, void *dirent,
-				filldir_t filldir,
+static bool proc_sys_fill_cache(struct file *file,
+				struct dir_context *ctx,
 				struct ctl_table_header *head,
 				struct ctl_table *table)
 {
-	struct dentry *child, *dir = filp->f_path.dentry;
+	struct dentry *child, *dir = file->f_path.dentry;
 	struct inode *inode;
 	struct qstr qname;
 	ino_t ino = 0;
@@ -595,38 +595,38 @@ static int proc_sys_fill_cache(struct file *filp, void *dirent,
 			inode = proc_sys_make_inode(dir->d_sb, head, table);
 			if (!inode) {
 				dput(child);
-				return -ENOMEM;
+				return false;
 			} else {
 				d_set_d_op(child, &proc_sys_dentry_operations);
 				d_add(child, inode);
 			}
 		} else {
-			return -ENOMEM;
+			return false;
 		}
 	}
 	inode = child->d_inode;
 	ino  = inode->i_ino;
 	type = inode->i_mode >> 12;
 	dput(child);
-	return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
+	return dir_emit(ctx, qname.name, qname.len, ino, type);
 }
 
-static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
-				    filldir_t filldir,
+static bool proc_sys_link_fill_cache(struct file *file,
+				    struct dir_context *ctx,
 				    struct ctl_table_header *head,
 				    struct ctl_table *table)
 {
-	int err, ret = 0;
+	bool ret = true;
 	head = sysctl_head_grab(head);
 
 	if (S_ISLNK(table->mode)) {
 		/* It is not an error if we can not follow the link ignore it */
-		err = sysctl_follow_link(&head, &table, current->nsproxy);
+		int err = sysctl_follow_link(&head, &table, current->nsproxy);
 		if (err)
 			goto out;
 	}
 
-	ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
+	ret = proc_sys_fill_cache(file, ctx, head, table);
 out:
 	sysctl_head_finish(head);
 	return ret;
@@ -634,67 +634,50 @@ out:
 
 static int scan(struct ctl_table_header *head, ctl_table *table,
 		unsigned long *pos, struct file *file,
-		void *dirent, filldir_t filldir)
+		struct dir_context *ctx)
 {
-	int res;
+	bool res;
 
-	if ((*pos)++ < file->f_pos)
-		return 0;
+	if ((*pos)++ < ctx->pos)
+		return true;
 
 	if (unlikely(S_ISLNK(table->mode)))
-		res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
+		res = proc_sys_link_fill_cache(file, ctx, head, table);
 	else
-		res = proc_sys_fill_cache(file, dirent, filldir, head, table);
+		res = proc_sys_fill_cache(file, ctx, head, table);
 
-	if (res == 0)
-		file->f_pos = *pos;
+	if (res)
+		ctx->pos = *pos;
 
 	return res;
 }
 
-static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
+static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
-	struct ctl_table_header *head = grab_header(inode);
+	struct ctl_table_header *head = grab_header(file_inode(file));
 	struct ctl_table_header *h = NULL;
 	struct ctl_table *entry;
 	struct ctl_dir *ctl_dir;
 	unsigned long pos;
-	int ret = -EINVAL;
 
 	if (IS_ERR(head))
 		return PTR_ERR(head);
 
 	ctl_dir = container_of(head, struct ctl_dir, header);
 
-	ret = 0;
-	/* Avoid a switch here: arm builds fail with missing __cmpdi2 */
-	if (filp->f_pos == 0) {
-		if (filldir(dirent, ".", 1, filp->f_pos,
-				inode->i_ino, DT_DIR) < 0)
-			goto out;
-		filp->f_pos++;
-	}
-	if (filp->f_pos == 1) {
-		if (filldir(dirent, "..", 2, filp->f_pos,
-				parent_ino(dentry), DT_DIR) < 0)
-			goto out;
-		filp->f_pos++;
-	}
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
 	pos = 2;
 
 	for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
-		ret = scan(h, entry, &pos, filp, dirent, filldir);
-		if (ret) {
+		if (!scan(h, entry, &pos, file, ctx)) {
 			sysctl_head_finish(h);
 			break;
 		}
 	}
-	ret = 1;
-out:
 	sysctl_head_finish(head);
-	return ret;
+	return 0;
 }
 
 static int proc_sys_permission(struct inode *inode, int mask)
@@ -769,7 +752,7 @@ static const struct file_operations proc_sys_file_operations = {
 
 static const struct file_operations proc_sys_dir_file_operations = {
 	.read		= generic_read_dir,
-	.readdir	= proc_sys_readdir,
+	.iterate	= proc_sys_readdir,
 	.llseek		= generic_file_llseek,
 };
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 41a6ea9..229e366 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -202,21 +202,14 @@ static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentr
 	return proc_pid_lookup(dir, dentry, flags);
 }
 
-static int proc_root_readdir(struct file * filp,
-	void * dirent, filldir_t filldir)
+static int proc_root_readdir(struct file *file, struct dir_context *ctx)
 {
-	unsigned int nr = filp->f_pos;
-	int ret;
-
-	if (nr < FIRST_PROCESS_ENTRY) {
-		int error = proc_readdir(filp, dirent, filldir);
-		if (error <= 0)
-			return error;
-		filp->f_pos = FIRST_PROCESS_ENTRY;
+	if (ctx->pos < FIRST_PROCESS_ENTRY) {
+		proc_readdir(file, ctx);
+		ctx->pos = FIRST_PROCESS_ENTRY;
 	}
 
-	ret = proc_pid_readdir(filp, dirent, filldir);
-	return ret;
+	return proc_pid_readdir(file, ctx);
 }
 
 /*
@@ -226,7 +219,7 @@ static int proc_root_readdir(struct file * filp,
  */
 static const struct file_operations proc_root_operations = {
 	.read		 = generic_read_dir,
-	.readdir	 = proc_root_readdir,
+	.iterate	 = proc_root_readdir,
 	.llseek		= default_llseek,
 };