linux/fs/gfs2/ops_file.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/blkdev.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/gfs2_ondisk.h>
#include <linux/ext2_fs.h>
#include <linux/crc32.h>
#include <linux/iflags.h>
#include <linux/lm_interface.h>
#include <asm/uaccess.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "dir.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "lm.h"
#include "log.h"
#include "meta_io.h"
#include "ops_file.h"
#include "ops_vm.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"
#include "util.h"
#include "eaops.h"

/* For regular, non-NFS */
struct filldir_reg {
	struct gfs2_sbd *fdr_sbd;
	int fdr_prefetch;

	filldir_t fdr_filldir;
	void *fdr_opaque;
};

/*
 * Most fields left uninitialised to catch anybody who tries to
 * use them. f_flags set to prevent file_accessed() from touching
 * any other part of this. Its use is purely as a flag so that we
 * know (in readpage()) whether or not do to locking.
 */
struct file gfs2_internal_file_sentinel = {
	.f_flags = O_NOATIME|O_RDONLY,
};

static int gfs2_read_actor(read_descriptor_t *desc, struct page *page,
			   unsigned long offset, unsigned long size)
{
	char *kaddr;
	unsigned long count = desc->count;

	if (size > count)
		size = count;

	kaddr = kmap(page);
	memcpy(desc->arg.buf, kaddr + offset, size);
	kunmap(page);

	desc->count = count - size;
	desc->written += size;
	desc->arg.buf += size;
	return size;
}

int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
		       char *buf, loff_t *pos, unsigned size)
{
	struct inode *inode = &ip->i_inode;
	read_descriptor_t desc;
	desc.written = 0;
	desc.arg.buf = buf;
	desc.count = size;
	desc.error = 0;
	do_generic_mapping_read(inode->i_mapping, ra_state,
				&gfs2_internal_file_sentinel, pos, &desc,
				gfs2_read_actor);
	return desc.written ? desc.written : desc.error;
}

/**
 * gfs2_llseek - seek to a location in a file
 * @file: the file
 * @offset: the offset
 * @origin: Where to seek from (SEEK_SET, SEEK_CUR, or SEEK_END)
 *
 * SEEK_END requires the glock for the file because it references the
 * file's size.
 *
 * Returns: The new offset, or errno
 */

static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_holder i_gh;
	loff_t error;

	if (origin == 2) {
		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
					   &i_gh);
		if (!error) {
			error = remote_llseek(file, offset, origin);
			gfs2_glock_dq_uninit(&i_gh);
		}
	} else
		error = remote_llseek(file, offset, origin);

	return error;
}

/**
 * filldir_func - Report a directory entry to the caller of gfs2_dir_read()
 * @opaque: opaque data used by the function
 * @name: the name of the directory entry
 * @length: the length of the name
 * @offset: the entry's offset in the directory
 * @inum: the inode number the entry points to
 * @type: the type of inode the entry points to
 *
 * Returns: 0 on success, 1 if buffer full
 */

static int filldir_func(void *opaque, const char *name, unsigned int length,
			u64 offset, struct gfs2_inum *inum,
			unsigned int type)
{
	struct filldir_reg *fdr = (struct filldir_reg *)opaque;
	struct gfs2_sbd *sdp = fdr->fdr_sbd;
	int error;

	error = fdr->fdr_filldir(fdr->fdr_opaque, name, length, offset,
				 inum->no_addr, type);
	if (error)
		return 1;

	if (fdr->fdr_prefetch && !(length == 1 && *name == '.')) {
		gfs2_glock_prefetch_num(sdp, inum->no_addr, &gfs2_inode_glops,
				       LM_ST_SHARED, LM_FLAG_TRY | LM_FLAG_ANY);
		gfs2_glock_prefetch_num(sdp, inum->no_addr, &gfs2_iopen_glops,
				       LM_ST_SHARED, LM_FLAG_TRY);
	}

	return 0;
}

/**
 * gfs2_readdir - Read directory entries from a directory
 * @file: The directory to read from
 * @dirent: Buffer for dirents
 * @filldir: Function used to do the copying
 *
 * Returns: errno
 */

static int gfs2_readdir(struct file *file, void *dirent, filldir_t filldir)
{
	struct inode *dir = file->f_mapping->host;
	struct gfs2_inode *dip = GFS2_I(dir);
	struct filldir_reg fdr;
	struct gfs2_holder d_gh;
	u64 offset = file->f_pos;
	int error;

	fdr.fdr_sbd = GFS2_SB(dir);
	fdr.fdr_prefetch = 1;
	fdr.fdr_filldir = filldir;
	fdr.fdr_opaque = dirent;

	gfs2_holder_init(dip->i_gl, LM_ST_SHARED, GL_ATIME, &d_gh);
	error = gfs2_glock_nq_atime(&d_gh);
	if (error) {
		gfs2_holder_uninit(&d_gh);
		return error;
	}

	error = gfs2_dir_read(dir, &offset, &fdr, filldir_func);

	gfs2_glock_dq_uninit(&d_gh);

	file->f_pos = offset;

	return error;
}


static const u32 iflags_to_gfs2[32] = {
	[iflag_Sync] = GFS2_DIF_SYNC,
	[iflag_Immutable] = GFS2_DIF_IMMUTABLE,
	[iflag_Append] = GFS2_DIF_APPENDONLY,
	[iflag_NoAtime] = GFS2_DIF_NOATIME,
	[iflag_Index] = GFS2_DIF_EXHASH,
	[iflag_JournalData] = GFS2_DIF_JDATA,
	[iflag_DirectIO] = GFS2_DIF_DIRECTIO,
};

static const u32 gfs2_to_iflags[32] = {
	[gfs2fl_Sync] = IFLAG_SYNC,
	[gfs2fl_Immutable] = IFLAG_IMMUTABLE,
	[gfs2fl_AppendOnly] = IFLAG_APPEND,
	[gfs2fl_NoAtime] = IFLAG_NOATIME,
	[gfs2fl_ExHash] = IFLAG_INDEX,
	[gfs2fl_Jdata] = IFLAG_JOURNAL_DATA,
	[gfs2fl_Directio] = IFLAG_DIRECTIO,
	[gfs2fl_InheritDirectio] = IFLAG_DIRECTIO,
	[gfs2fl_InheritJdata] = IFLAG_JOURNAL_DATA,
};

static int gfs2_get_flags(struct file *filp, u32 __user *ptr)
{
	struct inode *inode = filp->f_dentry->d_inode;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_holder gh;
	int error;
	u32 iflags;

	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
	error = gfs2_glock_nq_m_atime(1, &gh);
	if (error)
		return error;
	
	iflags = iflags_cvt(gfs2_to_iflags, ip->i_di.di_flags);
	if (put_user(iflags, ptr))
		error = -EFAULT;

	gfs2_glock_dq_m(1, &gh);
	gfs2_holder_uninit(&gh);
	return error;
}

/* Flags that can be set by user space */
#define GFS2_FLAGS_USER_SET (GFS2_DIF_JDATA|			\
			     GFS2_DIF_DIRECTIO|			\
			     GFS2_DIF_IMMUTABLE|		\
			     GFS2_DIF_APPENDONLY|		\
			     GFS2_DIF_NOATIME|			\
			     GFS2_DIF_SYNC|			\
			     GFS2_DIF_SYSTEM|			\
			     GFS2_DIF_INHERIT_DIRECTIO|		\
			     GFS2_DIF_INHERIT_JDATA)

/**
 * gfs2_set_flags - set flags on an inode
 * @inode: The inode
 * @flags: The flags to set
 * @mask: Indicates which flags are valid
 *
 */
static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
{
	struct inode *inode = filp->f_dentry->d_inode;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct buffer_head *bh;
	struct gfs2_holder gh;
	int error;
	u32 new_flags, flags;

	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
	if (error)
		return error;

	flags = ip->i_di.di_flags;
	new_flags = (flags & ~mask) | (reqflags & mask);
	if ((new_flags ^ flags) == 0)
		goto out;

	if (S_ISDIR(inode->i_mode)) {
		if ((new_flags ^ flags) & GFS2_DIF_JDATA)
			new_flags ^= (GFS2_DIF_JDATA|GFS2_DIF_INHERIT_JDATA);
		if ((new_flags ^ flags) & GFS2_DIF_DIRECTIO)
			new_flags ^= (GFS2_DIF_DIRECTIO|GFS2_DIF_INHERIT_DIRECTIO);
	}

	error = -EINVAL;
	if ((new_flags ^ flags) & ~GFS2_FLAGS_USER_SET)
		goto out;

	error = -EPERM;
	if (IS_IMMUTABLE(inode) && (new_flags & GFS2_DIF_IMMUTABLE))
		goto out;
	if (IS_APPEND(inode) && (new_flags & GFS2_DIF_APPENDONLY))
		goto out;
	if (((new_flags ^ flags) & GFS2_DIF_IMMUTABLE) && 
	    !capable(CAP_LINUX_IMMUTABLE))
		goto out;
	if (!IS_IMMUTABLE(inode)) {
		error = permission(inode, MAY_WRITE, NULL);
		if (error)
			goto out;
	}

	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		goto out;
	error = gfs2_meta_inode_buffer(ip, &bh);
	if (error)
		goto out_trans_end;
	gfs2_trans_add_bh(ip->i_gl, bh, 1);
	ip->i_di.di_flags = new_flags;
	gfs2_dinode_out(&ip->i_di, bh->b_data);
	brelse(bh);
out_trans_end:
	gfs2_trans_end(sdp);
out:
	gfs2_glock_dq_uninit(&gh);
	return error;
}

static int gfs2_set_flags(struct file *filp, u32 __user *ptr)
{
	u32 iflags, gfsflags;
	if (get_user(iflags, ptr))
		return -EFAULT;
	gfsflags = iflags_cvt(iflags_to_gfs2, iflags);
	return do_gfs2_set_flags(filp, gfsflags, ~0);
}

static long gfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	switch(cmd) {
	case IFLAGS_GET_IOC:
		return gfs2_get_flags(filp, (u32 __user *)arg);
	case IFLAGS_SET_IOC:
		return gfs2_set_flags(filp, (u32 __user *)arg);
	}
	return -ENOTTY;
}


/**
 * gfs2_mmap -
 * @file: The file to map
 * @vma: The VMA which described the mapping
 *
 * Returns: 0 or error code
 */

static int gfs2_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_holder i_gh;
	int error;

	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &i_gh);
	error = gfs2_glock_nq_atime(&i_gh);
	if (error) {
		gfs2_holder_uninit(&i_gh);
		return error;
	}

	/* This is VM_MAYWRITE instead of VM_WRITE because a call
	   to mprotect() can turn on VM_WRITE later. */

	if ((vma->vm_flags & (VM_MAYSHARE | VM_MAYWRITE)) ==
	    (VM_MAYSHARE | VM_MAYWRITE))
		vma->vm_ops = &gfs2_vm_ops_sharewrite;
	else
		vma->vm_ops = &gfs2_vm_ops_private;

	gfs2_glock_dq_uninit(&i_gh);

	return error;
}

/**
 * gfs2_open - open a file
 * @inode: the inode to open
 * @file: the struct file for this opening
 *
 * Returns: errno
 */

static int gfs2_open(struct inode *inode, struct file *file)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_holder i_gh;
	struct gfs2_file *fp;
	int error;

	fp = kzalloc(sizeof(struct gfs2_file), GFP_KERNEL);
	if (!fp)
		return -ENOMEM;

	mutex_init(&fp->f_fl_mutex);

	gfs2_assert_warn(GFS2_SB(inode), !file->private_data);
	file->private_data = fp;

	if (S_ISREG(ip->i_di.di_mode)) {
		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
					   &i_gh);
		if (error)
			goto fail;

		if (!(file->f_flags & O_LARGEFILE) &&
		    ip->i_di.di_size > MAX_NON_LFS) {
			error = -EFBIG;
			goto fail_gunlock;
		}

		/* Listen to the Direct I/O flag */

		if (ip->i_di.di_flags & GFS2_DIF_DIRECTIO)
			file->f_flags |= O_DIRECT;

		gfs2_glock_dq_uninit(&i_gh);
	}

	return 0;

fail_gunlock:
	gfs2_glock_dq_uninit(&i_gh);
fail:
	file->private_data = NULL;
	kfree(fp);
	return error;
}

/**
 * gfs2_close - called to close a struct file
 * @inode: the inode the struct file belongs to
 * @file: the struct file being closed
 *
 * Returns: errno
 */

static int gfs2_close(struct inode *inode, struct file *file)
{
	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
	struct gfs2_file *fp;

	fp = file->private_data;
	file->private_data = NULL;

	if (gfs2_assert_warn(sdp, fp))
		return -EIO;

	kfree(fp);

	return 0;
}

/**
 * gfs2_fsync - sync the dirty data for a file (across the cluster)
 * @file: the file that points to the dentry (we ignore this)
 * @dentry: the dentry that points to the inode to sync
 *
 * Returns: errno
 */

static int gfs2_fsync(struct file *file, struct dentry *dentry, int datasync)
{
	struct gfs2_inode *ip = GFS2_I(dentry->d_inode);

	gfs2_log_flush(ip->i_gl->gl_sbd, ip->i_gl);

	return 0;
}

/**
 * gfs2_lock - acquire/release a posix lock on a file
 * @file: the file pointer
 * @cmd: either modify or retrieve lock state, possibly wait
 * @fl: type and range of lock
 *
 * Returns: errno
 */

static int gfs2_lock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);
	struct lm_lockname name =
		{ .ln_number = ip->i_num.no_addr,
		  .ln_type = LM_TYPE_PLOCK };

	if (!(fl->fl_flags & FL_POSIX))
		return -ENOLCK;
	if ((ip->i_di.di_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
		return -ENOLCK;

	if (sdp->sd_args.ar_localflocks) {
		if (IS_GETLK(cmd)) {
			struct file_lock tmp;
			int ret;
			ret = posix_test_lock(file, fl, &tmp);
			fl->fl_type = F_UNLCK;
			if (ret)
				memcpy(fl, &tmp, sizeof(struct file_lock));
			return 0;
		} else {
			return posix_lock_file_wait(file, fl);
		}
	}

	if (IS_GETLK(cmd))
		return gfs2_lm_plock_get(sdp, &name, file, fl);
	else if (fl->fl_type == F_UNLCK)
		return gfs2_lm_punlock(sdp, &name, file, fl);
	else
		return gfs2_lm_plock(sdp, &name, file, cmd, fl);
}

static int do_flock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_file *fp = file->private_data;
	struct gfs2_holder *fl_gh = &fp->f_fl_gh;
	struct gfs2_inode *ip = GFS2_I(file->f_dentry->d_inode);
	struct gfs2_glock *gl;
	unsigned int state;
	int flags;
	int error = 0;

	state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED;
	flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE;

	mutex_lock(&fp->f_fl_mutex);

	gl = fl_gh->gh_gl;
	if (gl) {
		if (fl_gh->gh_state == state)
			goto out;
		gfs2_glock_hold(gl);
		flock_lock_file_wait(file,
				     &(struct file_lock){.fl_type = F_UNLCK});		
		gfs2_glock_dq_uninit(fl_gh);
	} else {
		error = gfs2_glock_get(GFS2_SB(&ip->i_inode),
				      ip->i_num.no_addr, &gfs2_flock_glops,
				      CREATE, &gl);
		if (error)
			goto out;
	}

	gfs2_holder_init(gl, state, flags, fl_gh);
	gfs2_glock_put(gl);

	error = gfs2_glock_nq(fl_gh);
	if (error) {
		gfs2_holder_uninit(fl_gh);
		if (error == GLR_TRYFAILED)
			error = -EAGAIN;
	} else {
		error = flock_lock_file_wait(file, fl);
		gfs2_assert_warn(GFS2_SB(&ip->i_inode), !error);
	}

out:
	mutex_unlock(&fp->f_fl_mutex);
	return error;
}

static void do_unflock(struct file *file, struct file_lock *fl)
{
	struct gfs2_file *fp = file->private_data;
	struct gfs2_holder *fl_gh = &fp->f_fl_gh;

	mutex_lock(&fp->f_fl_mutex);
	flock_lock_file_wait(file, fl);
	if (fl_gh->gh_gl)
		gfs2_glock_dq_uninit(fl_gh);
	mutex_unlock(&fp->f_fl_mutex);
}

/**
 * gfs2_flock - acquire/release a flock lock on a file
 * @file: the file pointer
 * @cmd: either modify or retrieve lock state, possibly wait
 * @fl: type and range of lock
 *
 * Returns: errno
 */

static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);

	if (!(fl->fl_flags & FL_FLOCK))
		return -ENOLCK;
	if ((ip->i_di.di_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
		return -ENOLCK;

	if (sdp->sd_args.ar_localflocks)
		return flock_lock_file_wait(file, fl);

	if (fl->fl_type == F_UNLCK) {
		do_unflock(file, fl);
		return 0;
	} else
		return do_flock(file, cmd, fl);
}

const struct file_operations gfs2_file_fops = {
	.llseek		= gfs2_llseek,
	.read		= generic_file_read,
	.readv		= generic_file_readv,
	.aio_read	= generic_file_aio_read,
	.write		= generic_file_write,
	.writev		= generic_file_writev,
	.aio_write	= generic_file_aio_write,
	.unlocked_ioctl	= gfs2_ioctl,
	.mmap		= gfs2_mmap,
	.open		= gfs2_open,
	.release	= gfs2_close,
	.fsync		= gfs2_fsync,
	.lock		= gfs2_lock,
	.sendfile	= generic_file_sendfile,
	.flock		= gfs2_flock,
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
};

const struct file_operations gfs2_dir_fops = {
	.readdir	= gfs2_readdir,
	.unlocked_ioctl	= gfs2_ioctl,
	.open		= gfs2_open,
	.release	= gfs2_close,
	.fsync		= gfs2_fsync,
	.lock		= gfs2_lock,
	.flock		= gfs2_flock,
};