[readdir] introduce iterate_dir() and dir_context

iterate_dir(): new helper, replacing vfs_readdir().

struct dir_context: contains the readdir callback (and will get more stuff
in it), embedded into whatever data that callback wants to deal with;
eventually, we'll be passing it to ->readdir() replacement instead of
(data,filldir) pair.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/porting

@@ -445,3 +445,6 @@ object doesn't exist.  It's remote/distributed ones that might care...
 [mandatory]
 	FS_REVAL_DOT is gone; if you used to have it, add ->d_weak_revalidate()
 in your dentry operations instead.
+--
+[mandatory]
+	vfs_readdir() is gone; switch to iterate_dir() instead

arch/alpha/kernel/osf_sys.c

@@ -96,6 +96,7 @@ struct osf_dirent {
 };
 
 struct osf_dirent_callback {
+	struct dir_context ctx;
 	struct osf_dirent __user *dirent;
 	long __user *basep;
 	unsigned int count;
@@ -155,8 +156,9 @@ SYSCALL_DEFINE4(osf_getdirentries, unsigned int, fd,
 	buf.basep = basep;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = osf_filldir;
 
-	error = vfs_readdir(arg.file, osf_filldir, &buf);
+	error = iterate_dir(arg.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	if (count != buf.count)

arch/parisc/hpux/fs.c

@@ -60,6 +60,7 @@ struct hpux_dirent {
 };
 
 struct getdents_callback {
+	struct dir_context ctx;
 	struct hpux_dirent __user *current_dir;
 	struct hpux_dirent __user *previous;
 	int count;
@@ -121,8 +122,9 @@ int hpux_getdents(unsigned int fd, struct hpux_dirent __user *dirent, unsigned i
 	buf.previous = NULL;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = filldir;
 
-	error = vfs_readdir(arg.file, filldir, &buf);
+	error = iterate_dir(arg.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	lastdirent = buf.previous;

fs/compat.c

@@ -832,6 +832,7 @@ struct compat_old_linux_dirent {
 };
 
 struct compat_readdir_callback {
+	struct dir_context ctx;
 	struct compat_old_linux_dirent __user *dirent;
 	int result;
 };
@@ -880,8 +881,9 @@ asmlinkage long compat_sys_old_readdir(unsigned int fd,
 
 	buf.result = 0;
 	buf.dirent = dirent;
+	buf.ctx.actor = compat_fillonedir;
 
-	error = vfs_readdir(f.file, compat_fillonedir, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (buf.result)
 		error = buf.result;
 
@@ -897,6 +899,7 @@ struct compat_linux_dirent {
 };
 
 struct compat_getdents_callback {
+	struct dir_context ctx;
 	struct compat_linux_dirent __user *current_dir;
 	struct compat_linux_dirent __user *previous;
 	int count;
@@ -965,8 +968,9 @@ asmlinkage long compat_sys_getdents(unsigned int fd,
 	buf.previous = NULL;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = compat_filldir;
 
-	error = vfs_readdir(f.file, compat_filldir, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	lastdirent = buf.previous;
@@ -983,6 +987,7 @@ asmlinkage long compat_sys_getdents(unsigned int fd,
 #ifndef __ARCH_OMIT_COMPAT_SYS_GETDENTS64
 
 struct compat_getdents_callback64 {
+	struct dir_context ctx;
 	struct linux_dirent64 __user *current_dir;
 	struct linux_dirent64 __user *previous;
 	int count;
@@ -1050,8 +1055,9 @@ asmlinkage long compat_sys_getdents64(unsigned int fd,
 	buf.previous = NULL;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = compat_filldir64;
 
-	error = vfs_readdir(f.file, compat_filldir64, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	lastdirent = buf.previous;

fs/ecryptfs/file.c

@@ -68,6 +68,7 @@ static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
 }
 
 struct ecryptfs_getdents_callback {
+	struct dir_context ctx;
 	void *dirent;
 	struct dentry *dentry;
 	filldir_t filldir;
@@ -126,7 +127,8 @@ static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 	buf.filldir = filldir;
 	buf.filldir_called = 0;
 	buf.entries_written = 0;
-	rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
+	buf.ctx.actor = ecryptfs_filldir;
+	rc = iterate_dir(lower_file, &buf.ctx);
 	file->f_pos = lower_file->f_pos;
 	if (rc < 0)
 		goto out;

fs/exportfs/expfs.c

@@ -212,6 +212,7 @@ reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf)
 }
 
 struct getdents_callback {
+	struct dir_context ctx;
 	char *name;		/* name that was found. It already points to a
 				   buffer NAME_MAX+1 is size */
 	unsigned long ino;	/* the inum we are looking for */
@@ -278,10 +279,11 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
 	buffer.ino = child->d_inode->i_ino;
 	buffer.found = 0;
 	buffer.sequence = 0;
+	buffer.ctx.actor = filldir_one;
 	while (1) {
 		int old_seq = buffer.sequence;
 
-		error = vfs_readdir(file, filldir_one, &buffer);
+		error = iterate_dir(file, &buffer.ctx);
 		if (buffer.found) {
 			error = 0;
 			break;

fs/nfsd/nfs4recover.c

@@ -263,7 +263,10 @@ nfsd4_list_rec_dir(recdir_func *f, struct nfsd_net *nn)
 {
 	const struct cred *original_cred;
 	struct dentry *dir = nn->rec_file->f_path.dentry;
-	LIST_HEAD(names);
+	struct {
+		struct dir_context ctx;
+		struct list_head names;
+	} ctx;
 	int status;
 
 	status = nfs4_save_creds(&original_cred);
@@ -276,11 +279,13 @@ nfsd4_list_rec_dir(recdir_func *f, struct nfsd_net *nn)
 		return status;
 	}
 
-	status = vfs_readdir(nn->rec_file, nfsd4_build_namelist, &names);
+	INIT_LIST_HEAD(&ctx.names);	
+	ctx.ctx.actor = nfsd4_build_namelist;
+	status = iterate_dir(nn->rec_file, &ctx.ctx);
 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
-	while (!list_empty(&names)) {
+	while (!list_empty(&ctx.names)) {
 		struct name_list *entry;
-		entry = list_entry(names.next, struct name_list, list);
+		entry = list_entry(ctx.names.next, struct name_list, list);
 		if (!status) {
 			struct dentry *dentry;
 			dentry = lookup_one_len(entry->name, dir, HEXDIR_LEN-1);

fs/nfsd/vfs.c

@@ -1912,6 +1912,7 @@ struct buffered_dirent {
 };
 
 struct readdir_data {
+	struct dir_context ctx;
 	char		*dirent;
 	size_t		used;
 	int		full;
@@ -1949,6 +1950,7 @@ static __be32 nfsd_buffered_readdir(struct file *file, filldir_t func,
 	int size;
 	loff_t offset;
 
+	buf.ctx.actor = nfsd_buffered_filldir;
 	buf.dirent = (void *)__get_free_page(GFP_KERNEL);
 	if (!buf.dirent)
 		return nfserrno(-ENOMEM);
@@ -1963,7 +1965,7 @@ static __be32 nfsd_buffered_readdir(struct file *file, filldir_t func,
 		buf.used = 0;
 		buf.full = 0;
 
-		host_err = vfs_readdir(file, nfsd_buffered_filldir, &buf);
+		host_err = iterate_dir(file, &buf.ctx);
 		if (buf.full)
 			host_err = 0;
 

fs/readdir.c

@@ -20,7 +20,7 @@
 
 #include <asm/uaccess.h>
 
-int vfs_readdir(struct file *file, filldir_t filler, void *buf)
+int iterate_dir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *inode = file_inode(file);
 	int res = -ENOTDIR;
@@ -37,15 +37,14 @@ int vfs_readdir(struct file *file, filldir_t filler, void *buf)
 
 	res = -ENOENT;
 	if (!IS_DEADDIR(inode)) {
-		res = file->f_op->readdir(file, buf, filler);
+		res = file->f_op->readdir(file, ctx, ctx->actor);
 		file_accessed(file);
 	}
 	mutex_unlock(&inode->i_mutex);
 out:
 	return res;
 }
-
-EXPORT_SYMBOL(vfs_readdir);
+EXPORT_SYMBOL(iterate_dir);
 
 /*
  * Traditional linux readdir() handling..
@@ -66,6 +65,7 @@ struct old_linux_dirent {
 };
 
 struct readdir_callback {
+	struct dir_context ctx;
 	struct old_linux_dirent __user * dirent;
 	int result;
 };
@@ -73,7 +73,7 @@ struct readdir_callback {
 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
 		      u64 ino, unsigned int d_type)
 {
-	struct readdir_callback * buf = (struct readdir_callback *) __buf;
+	struct readdir_callback *buf = (struct readdir_callback *) __buf;
 	struct old_linux_dirent __user * dirent;
 	unsigned long d_ino;
 
@@ -112,10 +112,11 @@ SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 	if (!f.file)
 		return -EBADF;
 
+	buf.ctx.actor = fillonedir;
 	buf.result = 0;
 	buf.dirent = dirent;
 
-	error = vfs_readdir(f.file, fillonedir, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (buf.result)
 		error = buf.result;
 
@@ -137,6 +138,7 @@ struct linux_dirent {
 };
 
 struct getdents_callback {
+	struct dir_context ctx;
 	struct linux_dirent __user * current_dir;
 	struct linux_dirent __user * previous;
 	int count;
@@ -205,8 +207,9 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
 	buf.previous = NULL;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = filldir;
 
-	error = vfs_readdir(f.file, filldir, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	lastdirent = buf.previous;
@@ -221,6 +224,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
 }
 
 struct getdents_callback64 {
+	struct dir_context ctx;
 	struct linux_dirent64 __user * current_dir;
 	struct linux_dirent64 __user * previous;
 	int count;
@@ -285,8 +289,9 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 	buf.previous = NULL;
 	buf.count = count;
 	buf.error = 0;
+	buf.ctx.actor = filldir64;
 
-	error = vfs_readdir(f.file, filldir64, &buf);
+	error = iterate_dir(f.file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	lastdirent = buf.previous;

include/linux/fs.h

@@ -1506,6 +1506,9 @@ int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
  * to have different dirent layouts depending on the binary type.
  */
 typedef int (*filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
+struct dir_context {
+	filldir_t actor;
+};
 struct block_device_operations;
 
 /* These macros are for out of kernel modules to test that
@@ -2494,6 +2497,7 @@ loff_t inode_get_bytes(struct inode *inode);
 void inode_set_bytes(struct inode *inode, loff_t bytes);
 
 extern int vfs_readdir(struct file *, filldir_t, void *);
+extern int iterate_dir(struct file *, struct dir_context *);
 
 extern int vfs_stat(const char __user *, struct kstat *);
 extern int vfs_lstat(const char __user *, struct kstat *);