patch-2.3.41 linux/fs/autofs4/root.c

• Lines: 625
• Date: Tue Jan 25 11:45:02 2000
• Orig file: v2.3.40/linux/fs/autofs4/root.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.40/linux/fs/autofs4/root.c linux/fs/autofs4/root.c
@@ -0,0 +1,624 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/autofs/root.c
+ *
+ *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *  Copyright 1999 Jeremy Fitzhardinge <jeremy@goop.org>
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#include <linux/errno.h>
+#include <linux/stat.h>
+#include <linux/param.h>
+#include "autofs_i.h"
+
+static int autofs4_dir_readdir(struct file *,void *,filldir_t);
+static struct dentry *autofs4_dir_lookup(struct inode *,struct dentry *);
+static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
+static int autofs4_dir_unlink(struct inode *,struct dentry *);
+static int autofs4_dir_rmdir(struct inode *,struct dentry *);
+static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
+static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
+static struct dentry *autofs4_root_lookup(struct inode *,struct dentry *);
+
+static struct file_operations autofs4_root_operations = {
+	readdir:	autofs4_dir_readdir,	/* readdir */
+	ioctl:		autofs4_root_ioctl,	/* ioctl */
+};
+
+struct inode_operations autofs4_root_inode_operations = {
+        &autofs4_root_operations,		/* file operations */
+
+	lookup:		autofs4_root_lookup,	/* lookup */
+	unlink:		autofs4_dir_unlink,      /* unlink */
+	symlink:	autofs4_dir_symlink,     /* symlink */
+	mkdir:		autofs4_dir_mkdir,       /* mkdir */
+	rmdir:		autofs4_dir_rmdir,       /* rmdir */
+};
+
+static struct file_operations autofs4_dir_operations = {
+        readdir:	autofs4_dir_readdir,     /* readdir */
+};
+
+struct inode_operations autofs4_dir_inode_operations = {
+        &autofs4_dir_operations, /* file operations */
+
+	lookup:		autofs4_dir_lookup,	/* lookup */
+        unlink:		autofs4_dir_unlink,      /* unlink */
+        symlink:	autofs4_dir_symlink,     /* symlink */
+        mkdir:		autofs4_dir_mkdir,       /* mkdir */
+        rmdir:		autofs4_dir_rmdir,       /* rmdir */
+};
+
+static inline struct dentry *nth_child(struct dentry *dir, int nr)
+{
+	struct list_head *tmp = dir->d_subdirs.next;
+
+	while(tmp != &dir->d_subdirs) {
+		if (nr-- == 0)
+			return list_entry(tmp, struct dentry, d_child);
+		tmp = tmp->next;
+	}
+	return NULL;
+}
+
+static int autofs4_dir_readdir(struct file *filp, void *dirent,
+			      filldir_t filldir)
+{
+	struct autofs_sb_info *sbi;
+	struct autofs_info *ino;
+	struct dentry *dentry = filp->f_dentry;
+	struct dentry *dent_ptr;
+	struct inode *dir = dentry->d_inode;
+	struct list_head *cursor;
+	off_t nr;
+
+	sbi = autofs4_sbi(dir->i_sb);
+	ino = autofs4_dentry_ino(dentry);
+	nr = filp->f_pos;
+
+	switch(nr)
+	{
+	case 0:
+		if (filldir(dirent, ".", 1, nr, dir->i_ino) < 0)
+			return 0;
+		filp->f_pos = ++nr;
+		/* fall through */
+	case 1:
+		if (filldir(dirent, "..", 2, nr, dentry->d_covers->d_parent->d_inode->i_ino) < 0)
+			return 0;
+		filp->f_pos = ++nr;
+		/* fall through */
+	default:
+		dent_ptr = nth_child(dentry, nr-2);
+		if (dent_ptr == NULL)
+			break;
+
+		cursor = &dent_ptr->d_child;
+
+		while(cursor != &dentry->d_subdirs) {
+			dent_ptr = list_entry(cursor, struct dentry, d_child);
+			if (dent_ptr->d_inode &&
+			    filldir(dirent, dent_ptr->d_name.name, dent_ptr->d_name.len, nr,
+				    dent_ptr->d_inode->i_ino) < 0)
+				return 0;
+			filp->f_pos = ++nr;
+			cursor = cursor->next;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+/* Update usage from here to top of tree, so that scan of
+   top-level directories will give a useful result */
+static void autofs4_update_usage(struct dentry *dentry)
+{
+	struct dentry *top = dentry->d_sb->s_root;
+
+	for(; dentry != top; dentry = dentry->d_parent) {
+		struct autofs_info *ino = autofs4_dentry_ino(dentry->d_covers);
+
+		if (ino) {
+			update_atime(dentry->d_inode);
+			ino->last_used = jiffies;
+		}
+	}
+}
+
+static int try_to_fill_dentry(struct dentry *dentry, 
+			      struct super_block *sb,
+			      struct autofs_sb_info *sbi)
+{
+	struct autofs_info *de_info = autofs4_dentry_ino(dentry);
+	int status = 0;
+
+	/* Block on any pending expiry here; invalidate the dentry
+           when expiration is done to trigger mount request with a new
+           dentry */
+	if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
+		DPRINTK(("try_to_fill_entry: waiting for expire %p name=%.*s, flags&PENDING=%s de_info=%p de_info->flags=%x\n",
+			 dentry, dentry->d_name.len, dentry->d_name.name, 
+			 dentry->d_flags & DCACHE_AUTOFS_PENDING?"t":"f",
+			 de_info, de_info?de_info->flags:0));
+		status = autofs4_wait(sbi, &dentry->d_name, NFY_NONE);
+		
+		DPRINTK(("try_to_fill_entry: expire done status=%d\n", status));
+		
+		return 0;
+	}
+
+	DPRINTK(("try_to_fill_entry: dentry=%p %.*s ino=%p\n", 
+		 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode));
+
+	/* Wait for a pending mount, triggering one if there isn't one already */
+	while(dentry->d_inode == NULL) {
+		DPRINTK(("try_to_fill_entry: waiting for mount name=%.*s, de_info=%p de_info->flags=%x\n",
+			 dentry->d_name.len, dentry->d_name.name, 
+			 de_info, de_info?de_info->flags:0));
+		status = autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT);
+		 
+		DPRINTK(("try_to_fill_entry: mount done status=%d\n", status));
+
+		if (status && dentry->d_inode)
+			return 0; /* Try to get the kernel to invalidate this dentry */
+		
+		/* Turn this into a real negative dentry? */
+		if (status == -ENOENT) {
+			dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
+			dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
+			return 1;
+		} else if (status) {
+			/* Return a negative dentry, but leave it "pending" */
+			return 1;
+		}
+		status = autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT);
+	}
+
+	/* If this is an unused directory that isn't a mount point,
+	   bitch at the daemon and fix it in user space */
+	if (S_ISDIR(dentry->d_inode->i_mode) &&
+	    dentry->d_mounts == dentry && 
+	    list_empty(&dentry->d_subdirs)) {
+		DPRINTK(("try_to_fill_entry: mounting existing dir\n"));
+		return autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT) == 0;
+	}
+
+	/* We don't update the usages for the autofs daemon itself, this
+	   is necessary for recursive autofs mounts */
+	if (!autofs4_oz_mode(sbi))
+		autofs4_update_usage(dentry);
+
+	dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
+	return 1;
+}
+
+
+/*
+ * Revalidate is called on every cache lookup.  Some of those
+ * cache lookups may actually happen while the dentry is not
+ * yet completely filled in, and revalidate has to delay such
+ * lookups..
+ */
+static int autofs4_root_revalidate(struct dentry * dentry, int flags)
+{
+	struct inode * dir = dentry->d_parent->d_inode;
+	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
+	struct autofs_info *ino;
+	int oz_mode = autofs4_oz_mode(sbi);
+
+	/* Pending dentry */
+	if (autofs4_ispending(dentry)) {
+		if (autofs4_oz_mode(sbi))
+			return 1;
+		else
+			return try_to_fill_dentry(dentry, dir->i_sb, sbi);
+	}
+
+	/* Negative dentry.. invalidate if "old" */
+	if (dentry->d_inode == NULL)
+		return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
+
+	ino = autofs4_dentry_ino(dentry);
+
+	/* Check for a non-mountpoint directory with no contents */
+	if (S_ISDIR(dentry->d_inode->i_mode) &&
+	    dentry->d_mounts == dentry && 
+	    list_empty(&dentry->d_subdirs)) {
+		DPRINTK(("autofs_root_revalidate: dentry=%p %.*s, emptydir\n",
+			 dentry, dentry->d_name.len, dentry->d_name.name));
+		if (autofs4_oz_mode(sbi))
+			return 1;
+		else
+			return try_to_fill_dentry(dentry, dir->i_sb, sbi);
+	}
+
+	/* Update the usage list */
+	if (!oz_mode)
+		autofs4_update_usage(dentry);
+
+	return 1;
+}
+
+static int autofs4_revalidate(struct dentry *dentry, int flags)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+
+	if (!autofs4_oz_mode(sbi))
+		autofs4_update_usage(dentry);
+
+	return 1;
+}
+
+static void autofs4_dentry_release(struct dentry *de)
+{
+	struct autofs_info *inf = autofs4_dentry_ino(de);
+
+	DPRINTK(("autofs4_dentry_release: releasing %p\n", de));
+
+	de->d_fsdata = NULL;
+	if (inf) {
+		inf->dentry = NULL;
+		inf->inode = NULL;
+
+		autofs4_free_ino(inf);
+	}
+}
+
+/* For dentries of directories in the root dir */
+static struct dentry_operations autofs4_root_dentry_operations = {
+	d_revalidate:	autofs4_root_revalidate,	/* d_revalidate */
+	d_release:	autofs4_dentry_release,
+};
+
+/* For other dentries */
+static struct dentry_operations autofs4_dentry_operations = {
+	d_revalidate:	autofs4_revalidate,	/* d_revalidate */
+	d_release:	autofs4_dentry_release,
+};
+
+/* Lookups in non-root dirs never find anything - if it's there, it's
+   already in the dcache */
+static struct dentry *autofs4_dir_lookup(struct inode *dir, struct dentry *dentry)
+{
+#if 0
+	DPRINTK(("autofs_dir_lookup: ignoring lookup of %.*s/%.*s\n",
+		 dentry->d_parent->d_name.len, dentry->d_parent->d_name.name,
+		 dentry->d_name.len, dentry->d_name.name));
+#endif
+
+	dentry->d_fsdata = NULL;
+	d_add(dentry, NULL);
+	return NULL;
+}
+
+/* Lookups in the root directory */
+static struct dentry *autofs4_root_lookup(struct inode *dir, struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi;
+	int oz_mode;
+
+	DPRINTK(("autofs_root_lookup: name = %.*s\n", 
+		 dentry->d_name.len, dentry->d_name.name));
+
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENOENT);/* File name too long to exist */
+
+	sbi = autofs4_sbi(dir->i_sb);
+
+	oz_mode = autofs4_oz_mode(sbi);
+	DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
+		 current->pid, current->pgrp, sbi->catatonic, oz_mode));
+
+	/*
+	 * Mark the dentry incomplete, but add it. This is needed so
+	 * that the VFS layer knows about the dentry, and we can count
+	 * on catching any lookups through the revalidate.
+	 *
+	 * Let all the hard work be done by the revalidate function that
+	 * needs to be able to do this anyway..
+	 *
+	 * We need to do this before we release the directory semaphore.
+	 */
+	if (dir->i_ino == AUTOFS_ROOT_INO)
+		dentry->d_op = &autofs4_root_dentry_operations;
+	else
+		dentry->d_op = &autofs4_dentry_operations;
+
+	dentry->d_flags |= DCACHE_AUTOFS_PENDING;
+	dentry->d_fsdata = NULL;
+	d_add(dentry, NULL);
+
+	if (dentry->d_op && dentry->d_op->d_revalidate) {
+		up(&dir->i_sem);
+		(dentry->d_op->d_revalidate)(dentry, 0);
+		down(&dir->i_sem);
+	}
+
+	/*
+	 * If we are still pending, check if we had to handle
+	 * a signal. If so we can force a restart..
+	 */
+	if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
+		if (signal_pending(current))
+			return ERR_PTR(-ERESTARTNOINTR);
+	}
+
+	/*
+	 * If this dentry is unhashed, then we shouldn't honour this
+	 * lookup even if the dentry is positive.  Returning ENOENT here
+	 * doesn't do the right thing for all system calls, but it should
+	 * be OK for the operations we permit from an autofs.
+	 */
+	if ( dentry->d_inode && list_empty(&dentry->d_hash) )
+		return ERR_PTR(-ENOENT);
+
+	return NULL;
+}
+
+static int autofs4_dir_symlink(struct inode *dir, 
+			       struct dentry *dentry,
+			       const char *symname)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+	struct inode *inode;
+	char *cp;
+
+	DPRINTK(("autofs_dir_symlink: %s <- %.*s\n", symname, 
+		 dentry->d_name.len, dentry->d_name.name));
+
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	if (!autofs4_oz_mode(sbi))
+		return -EACCES;
+
+	if (dentry->d_name.len > NAME_MAX)
+		return -ENAMETOOLONG;
+
+	if (dentry->d_inode != NULL)
+		return -EEXIST;
+
+	ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
+	if (ino == NULL)
+		return -ENOSPC;
+
+	ino->size = strlen(symname);
+	ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
+
+	if (cp == NULL) {
+		kfree(ino);
+		return -ENOSPC;
+	}
+
+	strcpy(cp, symname);
+
+	autofs4_ihash_insert(&sbi->ihash, ino);
+	inode = iget(dir->i_sb,ino->ino);
+	d_instantiate(dentry, inode);
+
+	if (dir->i_ino == AUTOFS_ROOT_INO)
+		dentry->d_op = &autofs4_root_dentry_operations;
+	else
+		dentry->d_op = &autofs4_dentry_operations;
+
+	dentry->d_fsdata = ino;
+	ino->dentry = dget(dentry);
+	ino->inode = inode;
+
+	dir->i_mtime = CURRENT_TIME;
+
+	return 0;
+}
+
+/*
+ * NOTE!
+ *
+ * Normal filesystems would do a "d_delete()" to tell the VFS dcache
+ * that the file no longer exists. However, doing that means that the
+ * VFS layer can turn the dentry into a negative dentry.  We don't want
+ * this, because since the unlink is probably the result of an expire.
+ * We simply d_drop it, which allows the dentry lookup to remount it
+ * if necessary.
+ *
+ * If a process is blocked on the dentry waiting for the expire to finish,
+ * it will invalidate the dentry and try to mount with a new one.
+ *
+ * Also see autofs_dir_rmdir().. 
+ */
+static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	if (dentry->d_inode == NULL)
+		return -ENOENT;
+	
+	/* This allows root to remove symlinks */
+	if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
+		return -EACCES;
+
+	dput(ino->dentry);
+
+	dentry->d_inode->i_size = 0;
+	dentry->d_inode->i_nlink = 0;
+
+	dir->i_mtime = CURRENT_TIME;
+
+	DPRINTK(("autofs_dir_unlink: unlinking %p %.*s, count=%d\n",
+		dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_count));
+
+	d_drop(dentry);
+	
+	return 0;
+}
+
+static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	if (dentry->d_inode == NULL)
+		return -ENOENT;
+	
+	if (!autofs4_oz_mode(sbi))
+		return -EACCES;
+
+	if (!list_empty(&dentry->d_subdirs))
+		return -ENOTEMPTY;
+
+	dput(ino->dentry);
+
+	dentry->d_inode->i_size = 0;
+	dentry->d_inode->i_nlink = 0;
+
+	if (dir->i_nlink)
+		dir->i_nlink--;
+
+	DPRINTK(("autofs_dir_rmdir: rmdir %p %.*s, count=%d\n",
+		dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_count));
+
+	d_drop(dentry);
+
+	return 0;
+}
+
+
+
+static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+	struct inode *inode;
+
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	if ( !autofs4_oz_mode(sbi) )
+		return -EACCES;
+
+	if ( dentry->d_inode != NULL )
+		return -EEXIST;
+	
+	if ( dentry->d_name.len > NAME_MAX )
+		return -ENAMETOOLONG;
+
+	DPRINTK(("autofs_dir_mkdir: dentry %p, creating %.*s\n",
+		 dentry, dentry->d_name.len, dentry->d_name.name));
+
+	ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
+	if (ino == NULL)
+		return -ENOSPC;
+
+	autofs4_ihash_insert(&sbi->ihash, ino);
+
+	inode = iget(dir->i_sb, ino->ino);
+	d_instantiate(dentry, inode);
+
+	if (dir->i_ino == AUTOFS_ROOT_INO)
+		dentry->d_op = &autofs4_root_dentry_operations;
+	else
+		dentry->d_op = &autofs4_dentry_operations;
+
+	dentry->d_fsdata = ino;
+	ino->dentry = dget(dentry);
+	ino->inode = inode;
+	dir->i_nlink++;
+	dir->i_mtime = CURRENT_TIME;
+
+	return 0;
+}
+
+/* Get/set timeout ioctl() operation */
+static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
+					 unsigned long *p)
+{
+	int rv;
+	unsigned long ntimeout;
+
+	if ( (rv = get_user(ntimeout, p)) ||
+	     (rv = put_user(sbi->exp_timeout/HZ, p)) )
+		return rv;
+
+	if ( ntimeout > ULONG_MAX/HZ )
+		sbi->exp_timeout = 0;
+	else
+		sbi->exp_timeout = ntimeout * HZ;
+
+	return 0;
+}
+
+/* Return protocol version */
+static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int *p)
+{
+	return put_user(sbi->version, p);
+}
+
+/* Identify autofs_dentries - this is so we can tell if there's
+   an extra dentry refcount or not.  We only hold a refcount on the
+   dentry if its non-negative (ie, d_inode != NULL)
+*/
+int is_autofs4_dentry(struct dentry *dentry)
+{
+	return dentry && dentry->d_inode &&
+		(dentry->d_op == &autofs4_root_dentry_operations ||
+		 dentry->d_op == &autofs4_dentry_operations) &&
+		dentry->d_fsdata != NULL;
+}
+
+/*
+ * ioctl()'s on the root directory is the chief method for the daemon to
+ * generate kernel reactions
+ */
+static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
+			     unsigned int cmd, unsigned long arg)
+{
+	struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
+
+	DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
+		 cmd,arg,sbi,current->pgrp));
+
+	if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
+	     _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
+		return -ENOTTY;
+	
+	if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
+		return -EPERM;
+	
+	switch(cmd) {
+	case AUTOFS_IOC_READY:	/* Wait queue: go ahead and retry */
+		return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
+	case AUTOFS_IOC_FAIL:	/* Wait queue: fail with ENOENT */
+		return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
+	case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
+		autofs4_catatonic_mode(sbi);
+		return 0;
+	case AUTOFS_IOC_PROTOVER: /* Get protocol version */
+		return autofs4_get_protover(sbi, (int *)arg);
+	case AUTOFS_IOC_SETTIMEOUT:
+		return autofs4_get_set_timeout(sbi,(unsigned long *)arg);
+
+	/* return a single thing to expire */
+	case AUTOFS_IOC_EXPIRE:
+		return autofs4_expire_run(inode->i_sb,sbi,
+					 (struct autofs_packet_expire *)arg);
+	/* same as above, but can send multiple expires through pipe */
+	case AUTOFS_IOC_EXPIRE_MULTI:
+		return autofs4_expire_multi(inode->i_sb, sbi, (int *)arg);
+
+	default:
+		return -ENOSYS;
+	}
+}