1 files changed, 175 insertions, 287 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c3834dad09b3..1485e38daaa3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1681,46 +1681,34 @@ 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 qstr qname = QSTR_INIT(name, len);
         struct inode *inode;
-        struct qstr qname;
-        ino_t ino = 0;
-        unsigned type = DT_UNKNOWN;
-
-        qname.name = name;
-        qname.len  = len;
-        qname.hash = full_name_hash(name, len);
+        unsigned type;
+        ino_t ino;
 
-        child = d_lookup(dir, &qname);
+        child = d_hash_and_lookup(dir, &qname);
         if (!child) {
-                struct dentry *new;
-                new = d_alloc(dir, &qname);
-                if (new) {
-                        child = instantiate(dir->d_inode, new, task, ptr);
-                        if (child)
-                                dput(new);
-                        else
-                                child = new;
+                child = d_alloc(dir, &qname);
+                if (!child)
+                        goto end_instantiate;
+                if (instantiate(dir->d_inode, child, task, ptr) < 0) {
+                        dput(child);
+                        goto end_instantiate;
                 }
         }
-        if (!child || IS_ERR(child) || !child->d_inode)
-                goto end_instantiate;
         inode = child->d_inode;
-        if (inode) {
-                ino = inode->i_ino;
-                type = inode->i_mode >> 12;
-        }
+        ino = inode->i_ino;
+        type = inode->i_mode >> 12;
         dput(child);
+        return dir_emit(ctx, name, len, ino, type);
+
 end_instantiate:
-        if (!ino)
-                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, 1, DT_UNKNOWN);
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1846,7 +1834,7 @@ struct map_files_info {
         unsigned char   name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
 };
 
-static struct dentry *
+static int
 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
                            struct task_struct *task, const void *ptr)
 {
@@ -1856,7 +1844,7 @@ proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
 
         inode = proc_pid_make_inode(dir->i_sb, task);
         if (!inode)
-                return ERR_PTR(-ENOENT);
+                return -ENOENT;
 
         ei = PROC_I(inode);
         ei->op.proc_get_link = proc_map_files_get_link;
@@ -1873,7 +1861,7 @@ proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
         d_set_d_op(dentry, &tid_map_files_dentry_operations);
         d_add(dentry, inode);
 
-        return NULL;
+        return 0;
 }
 
 static struct dentry *proc_map_files_lookup(struct inode *dir,
@@ -1882,23 +1870,23 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
         unsigned long vm_start, vm_end;
         struct vm_area_struct *vma;
         struct task_struct *task;
-        struct dentry *result;
+        int result;
         struct mm_struct *mm;
 
-        result = ERR_PTR(-EPERM);
+        result = -EPERM;
         if (!capable(CAP_SYS_ADMIN))
                 goto out;
 
-        result = ERR_PTR(-ENOENT);
+        result = -ENOENT;
         task = get_proc_task(dir);
         if (!task)
                 goto out;
 
-        result = ERR_PTR(-EACCES);
+        result = -EACCES;
         if (!ptrace_may_access(task, PTRACE_MODE_READ))
                 goto out_put_task;
 
-        result = ERR_PTR(-ENOENT);
+        result = -ENOENT;
         if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
                 goto out_put_task;
 
@@ -1921,7 +1909,7 @@ out_no_vma:
 out_put_task:
         put_task_struct(task);
 out:
-        return result;
+        return ERR_PTR(result);
 }
 
 static const struct inode_operations proc_map_files_inode_operations = {
@@ -1931,14 +1919,15 @@ 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 +1935,7 @@ 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 +1944,73 @@ 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 +2020,7 @@ 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,
 };
 
@@ -2152,13 +2123,12 @@ static const struct file_operations proc_timers_operations = {
 };
 #endif /* CONFIG_CHECKPOINT_RESTORE */
 
-static struct dentry *proc_pident_instantiate(struct inode *dir,
+static int proc_pident_instantiate(struct inode *dir,
         struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
         const struct pid_entry *p = ptr;
         struct inode *inode;
         struct proc_inode *ei;
-        struct dentry *error = ERR_PTR(-ENOENT);
 
         inode = proc_pid_make_inode(dir->i_sb, task);
         if (!inode)
@@ -2177,9 +2147,9 @@ static struct dentry *proc_pident_instantiate(struct inode *dir,
         d_add(dentry, inode);
         /* Close the race of the process dying before we return the dentry */
         if (pid_revalidate(dentry, 0))
-                error = NULL;
+                return 0;
 out:
-        return error;
+        return -ENOENT;
 }
 
 static struct dentry *proc_pident_lookup(struct inode *dir, 
@@ -2187,11 +2157,11 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
                                          const struct pid_entry *ents,
                                          unsigned int nents)
 {
-        struct dentry *error;
+        int error;
         struct task_struct *task = get_proc_task(dir);
         const struct pid_entry *p, *last;
 
-        error = ERR_PTR(-ENOENT);
+        error = -ENOENT;
 
         if (!task)
                 goto out_no_task;
@@ -2214,70 +2184,33 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
 out:
         put_task_struct(task);
 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);
+        return ERR_PTR(error);
 }
 
-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 +2295,15 @@ 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 +2657,15 @@ 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,
 };
 
@@ -2836,11 +2767,10 @@ void proc_flush_task(struct task_struct *task)
         }
 }
 
-static struct dentry *proc_pid_instantiate(struct inode *dir,
-                                           struct dentry * dentry,
-                                           struct task_struct *task, const void *ptr)
+static int proc_pid_instantiate(struct inode *dir,
+                                   struct dentry * dentry,
+                                   struct task_struct *task, const void *ptr)
 {
-        struct dentry *error = ERR_PTR(-ENOENT);
         struct inode *inode;
 
         inode = proc_pid_make_inode(dir->i_sb, task);
@@ -2860,14 +2790,14 @@ static struct dentry *proc_pid_instantiate(struct inode *dir,
         d_add(dentry, inode);
         /* Close the race of the process dying before we return the dentry */
         if (pid_revalidate(dentry, 0))
-                error = NULL;
+                return 0;
 out:
-        return error;
+        return -ENOENT;
 }
 
 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
 {
-        struct dentry *result = NULL;
+        int result = 0;
         struct task_struct *task;
         unsigned tgid;
         struct pid_namespace *ns;
@@ -2888,7 +2818,7 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
         result = proc_pid_instantiate(dir, dentry, task, NULL);
         put_task_struct(task);
 out:
-        return result;
+        return ERR_PTR(result);
 }
 
 /*
@@ -2936,58 +2866,42 @@ 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;
+        struct pid_namespace *ns = file->f_dentry->d_sb->s_fs_info;
+        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;
+                struct inode *inode = ns->proc_self->d_inode;
+                if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
+                        return 0;
                 iter.tgid = 0;
         } else {
                 iter.tgid = pos - TGID_OFFSET;
         }
         iter.task = NULL;
-        ns = filp->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 +2989,10 @@ 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 +3003,7 @@ 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,
 };
 
@@ -3100,10 +3013,9 @@ static const struct inode_operations proc_tid_base_inode_operations = {
         .setattr        = proc_setattr,
 };
 
-static struct dentry *proc_task_instantiate(struct inode *dir,
+static int proc_task_instantiate(struct inode *dir,
         struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
-        struct dentry *error = ERR_PTR(-ENOENT);
         struct inode *inode;
         inode = proc_pid_make_inode(dir->i_sb, task);
 
@@ -3122,14 +3034,14 @@ static struct dentry *proc_task_instantiate(struct inode *dir,
         d_add(dentry, inode);
         /* Close the race of the process dying before we return the dentry */
         if (pid_revalidate(dentry, 0))
-                error = NULL;
+                return 0;
 out:
-        return error;
+        return -ENOENT;
 }
 
 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
 {
-        struct dentry *result = ERR_PTR(-ENOENT);
+        int result = -ENOENT;
         struct task_struct *task;
         struct task_struct *leader = get_proc_task(dir);
         unsigned tid;
@@ -3159,7 +3071,7 @@ out_drop_task:
 out:
         put_task_struct(leader);
 out_no_task:
-        return result;
+        return ERR_PTR(result);
 }
 
 /*
@@ -3231,30 +3143,16 @@ 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 +3161,36 @@ 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 +3216,6 @@ 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,
 };