mm: fix fault vs invalidate race for linear mappings

[deliverable/linux.git] / 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/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/fs.h>
#include <linux/gfs2_ondisk.h>
#include <linux/ext2_fs.h>
#include <linux/crc32.h>
#include <linux/lm_interface.h>
#include <linux/writeback.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"

/*
 * 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.data, 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.data = 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;
}

/**
 * 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 gfs2_holder d_gh;
        u64 offset = file->f_pos;
        int error;

        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, dirent, filldir);

        gfs2_glock_dq_uninit(&d_gh);

        file->f_pos = offset;

        return error;
}

/**
 * fsflags_cvt
 * @table: A table of 32 u32 flags
 * @val: a 32 bit value to convert
 *
 * This function can be used to convert between fsflags values and
 * GFS2's own flags values.
 *
 * Returns: the converted flags
 */
static u32 fsflags_cvt(const u32 *table, u32 val)
{
        u32 res = 0;
        while(val) {
                if (val & 1)
                        res |= *table;
                table++;
                val >>= 1;
        }
        return res;
}

static const u32 fsflags_to_gfs2[32] = {
        [3] = GFS2_DIF_SYNC,
        [4] = GFS2_DIF_IMMUTABLE,
        [5] = GFS2_DIF_APPENDONLY,
        [7] = GFS2_DIF_NOATIME,
        [12] = GFS2_DIF_EXHASH,
        [14] = GFS2_DIF_JDATA,
        [20] = GFS2_DIF_DIRECTIO,
};

static const u32 gfs2_to_fsflags[32] = {
        [gfs2fl_Sync] = FS_SYNC_FL,
        [gfs2fl_Immutable] = FS_IMMUTABLE_FL,
        [gfs2fl_AppendOnly] = FS_APPEND_FL,
        [gfs2fl_NoAtime] = FS_NOATIME_FL,
        [gfs2fl_ExHash] = FS_INDEX_FL,
        [gfs2fl_Jdata] = FS_JOURNAL_DATA_FL,
        [gfs2fl_Directio] = FS_DIRECTIO_FL,
        [gfs2fl_InheritDirectio] = FS_DIRECTIO_FL,
        [gfs2fl_InheritJdata] = FS_JOURNAL_DATA_FL,
};

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

        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
        error = gfs2_glock_nq_atime(&gh);
        if (error)
                return error;

        fsflags = fsflags_cvt(gfs2_to_fsflags, ip->i_di.di_flags);
        if (put_user(fsflags, ptr))
                error = -EFAULT;

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

void gfs2_set_inode_flags(struct inode *inode)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_dinode_host *di = &ip->i_di;
        unsigned int flags = inode->i_flags;

        flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
        if (di->di_flags & GFS2_DIF_IMMUTABLE)
                flags |= S_IMMUTABLE;
        if (di->di_flags & GFS2_DIF_APPENDONLY)
                flags |= S_APPEND;
        if (di->di_flags & GFS2_DIF_NOATIME)
                flags |= S_NOATIME;
        if (di->di_flags & GFS2_DIF_SYNC)
                flags |= S_SYNC;
        inode->i_flags = flags;
}

/* 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_path.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, bh->b_data);
        brelse(bh);
        gfs2_set_inode_flags(inode);
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 fsflags, gfsflags;
        if (get_user(fsflags, ptr))
                return -EFAULT;
        gfsflags = fsflags_cvt(fsflags_to_gfs2, fsflags);
        return do_gfs2_set_flags(filp, gfsflags, ~0);
}

static long gfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        switch(cmd) {
        case FS_IOC_GETFLAGS:
                return gfs2_get_flags(filp, (u32 __user *)arg);
        case FS_IOC_SETFLAGS:
                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;

        vma->vm_flags |= VM_CAN_INVALIDATE;

        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_inode.i_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
 *
 * The VFS will flush "normal" data for us. We only need to worry
 * about metadata here. For journaled data, we just do a log flush
 * as we can't avoid it. Otherwise we can just bale out if datasync
 * is set. For stuffed inodes we must flush the log in order to
 * ensure that all data is on disk.
 *
 * The call to write_inode_now() is there to write back metadata and
 * the inode itself. It does also try and write the data, but thats
 * (hopefully) a no-op due to the VFS having already called filemap_fdatawrite()
 * for us.
 *
 * Returns: errno
 */

static int gfs2_fsync(struct file *file, struct dentry *dentry, int datasync)
{
        struct inode *inode = dentry->d_inode;
        int sync_state = inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC);
        int ret = 0;

        if (gfs2_is_jdata(GFS2_I(inode))) {
                gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl);
                return 0;
        }

        if (sync_state != 0) {
                if (!datasync)
                        ret = write_inode_now(inode, 0);

                if (gfs2_is_stuffed(GFS2_I(inode)))
                        gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl);
        }

        return ret;
}

/**
 * gfs2_setlease - acquire/release a file lease
 * @file: the file pointer
 * @arg: lease type
 * @fl: file lock
 *
 * Returns: errno
 */

static int gfs2_setlease(struct file *file, long arg, struct file_lock **fl)
{
        struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);

        /*
         * We don't currently have a way to enforce a lease across the whole
         * cluster; until we do, disable leases (by just returning -EINVAL),
         * unless the administrator has requested purely local locking.
         */
        if (!sdp->sd_args.ar_localflocks)
                return -EINVAL;
        return setlease(file, arg, fl);
}

/**
 * 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_no_addr,
                  .ln_type = LM_TYPE_PLOCK };

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

        if (sdp->sd_args.ar_localflocks) {
                if (IS_GETLK(cmd)) {
                        posix_test_lock(file, fl);
                        return 0;
                } else {
                        return posix_lock_file_wait(file, fl);
                }
        }

        if (cmd == F_CANCELLK) {
                /* Hack: */
                cmd = F_SETLK;
                fl->fl_type = F_UNLCK;
        }
        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_path.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_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_inode.i_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           = do_sync_read,
        .aio_read       = generic_file_aio_read,
        .write          = do_sync_write,
        .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,
        .flock          = gfs2_flock,
        .splice_read    = generic_file_splice_read,
        .splice_write   = generic_file_splice_write,
        .setlease       = gfs2_setlease,
};

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,
};