/*
 * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */
/*
 *  fs/xfs/linux/xfs_lrw.c (Linux Read Write stuff)
 *
 */

#include "xfs.h"

#include "xfs_fs.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_alloc.h"
#include "xfs_dmapi.h"
#include "xfs_quota.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_bit.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_itable.h"
#include "xfs_rw.h"
#include "xfs_refcache.h"
#include "xfs_acl.h"
#include "xfs_cap.h"
#include "xfs_mac.h"
#include "xfs_attr.h"
#include "xfs_inode_item.h"
#include "xfs_buf_item.h"
#include "xfs_utils.h"
#include "xfs_iomap.h"

#include <linux/capability.h>


#if defined(XFS_RW_TRACE)
void
xfs_rw_enter_trace(
        int             tag,
        xfs_iocore_t    *io,
        const char      *buf,
        size_t          size,
        loff_t          offset,
        int             ioflags)
{
        xfs_inode_t     *ip = XFS_IO_INODE(io);

        if (ip->i_rwtrace == NULL)
                return;
        ktrace_enter(ip->i_rwtrace,
                (void *)(unsigned long)tag,
                (void *)ip,
                (void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
                (void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
                (void *)(__psint_t)buf,
                (void *)((unsigned long)size),
                (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
                (void *)((unsigned long)(offset & 0xffffffff)),
                (void *)((unsigned long)ioflags),
                (void *)((unsigned long)((io->io_new_size >> 32) & 0xffffffff)),
                (void *)((unsigned long)(io->io_new_size & 0xffffffff)),
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL);
}

void
xfs_inval_cached_trace(
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        xfs_off_t       len,
        xfs_off_t       first,
        xfs_off_t       last)
{
        xfs_inode_t     *ip = XFS_IO_INODE(io);

        if (ip->i_rwtrace == NULL)
                return;
        ktrace_enter(ip->i_rwtrace,
                (void *)(__psint_t)XFS_INVAL_CACHED,
                (void *)ip,
                (void *)((unsigned long)((offset >> 32) & 0xffffffff)),
                (void *)((unsigned long)(offset & 0xffffffff)),
                (void *)((unsigned long)((len >> 32) & 0xffffffff)),
                (void *)((unsigned long)(len & 0xffffffff)),
                (void *)((unsigned long)((first >> 32) & 0xffffffff)),
                (void *)((unsigned long)(first & 0xffffffff)),
                (void *)((unsigned long)((last >> 32) & 0xffffffff)),
                (void *)((unsigned long)(last & 0xffffffff)),
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL,
                (void *)NULL);
}
#endif

/*
 *      xfs_iozero
 *
 *      xfs_iozero clears the specified range of buffer supplied,
 *      and marks all the affected blocks as valid and modified.  If
 *      an affected block is not allocated, it will be allocated.  If
 *      an affected block is not completely overwritten, and is not
 *      valid before the operation, it will be read from disk before
 *      being partially zeroed.
 */
STATIC int
xfs_iozero(
        struct inode            *ip,    /* inode                        */
        loff_t                  pos,    /* offset in file               */
        size_t                  count,  /* size of data to zero         */
        loff_t                  end_size)       /* max file size to set */
{
        unsigned                bytes;
        struct page             *page;
        struct address_space    *mapping;
        char                    *kaddr;
        int                     status;

        mapping = ip->i_mapping;
        do {
                unsigned long index, offset;

                offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
                index = pos >> PAGE_CACHE_SHIFT;
                bytes = PAGE_CACHE_SIZE - offset;
                if (bytes > count)
                        bytes = count;

                status = -ENOMEM;
                page = grab_cache_page(mapping, index);
                if (!page)
                        break;

                kaddr = kmap(page);
                status = mapping->a_ops->prepare_write(NULL, page, offset,
                                                        offset + bytes);
                if (status) {
                        goto unlock;
                }

                memset((void *) (kaddr + offset), 0, bytes);
                flush_dcache_page(page);
                status = mapping->a_ops->commit_write(NULL, page, offset,
                                                        offset + bytes);
                if (!status) {
                        pos += bytes;
                        count -= bytes;
                        if (pos > i_size_read(ip))
                                i_size_write(ip, pos < end_size ? pos : end_size);
                }

unlock:
                kunmap(page);
                unlock_page(page);
                page_cache_release(page);
                if (status)
                        break;
        } while (count);

        return (-status);
}

/*
 * xfs_inval_cached_pages
 * 
 * This routine is responsible for keeping direct I/O and buffered I/O
 * somewhat coherent.  From here we make sure that we're at least
 * temporarily holding the inode I/O lock exclusively and then call
 * the page cache to flush and invalidate any cached pages.  If there
 * are no cached pages this routine will be very quick.
 */
void
xfs_inval_cached_pages(
        vnode_t         *vp,
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        int             write,
        int             relock)
{
        xfs_mount_t     *mp;

        if (!VN_CACHED(vp)) {
                return;
        }

        mp = io->io_mount;

        /*
         * We need to get the I/O lock exclusively in order
         * to safely invalidate pages and mappings.
         */
        if (relock) {
                XFS_IUNLOCK(mp, io, XFS_IOLOCK_SHARED);
                XFS_ILOCK(mp, io, XFS_IOLOCK_EXCL);
        }

        /* Writing beyond EOF creates a hole that must be zeroed */
        if (write && (offset > XFS_SIZE(mp, io))) {
                xfs_fsize_t     isize;

                XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
                isize = XFS_SIZE(mp, io);
                if (offset > isize) {
                        xfs_zero_eof(vp, io, offset, isize, offset);
                }
                XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
        }

        xfs_inval_cached_trace(io, offset, -1, ctooff(offtoct(offset)), -1);
        VOP_FLUSHINVAL_PAGES(vp, ctooff(offtoct(offset)), -1, FI_REMAPF_LOCKED);
        if (relock) {
                XFS_ILOCK_DEMOTE(mp, io, XFS_IOLOCK_EXCL);
        }
}

ssize_t                 /* bytes read, or (-)  error */
xfs_read(
        bhv_desc_t      *bdp,
        struct file     *file,
        char            *buf,
        size_t          size,
        loff_t          *offset,
        int             ioflags,
        cred_t          *credp)
{
        ssize_t         ret;
        xfs_fsize_t     n;
        xfs_inode_t     *ip;
        xfs_mount_t     *mp;

        ip = XFS_BHVTOI(bdp);
        mp = ip->i_mount;

        XFS_STATS_INC(xs_read_calls);

        if (unlikely(ioflags & IO_ISDIRECT)) {
                if ((ssize_t)size < 0)
                        return -XFS_ERROR(EINVAL);
                if (((__psint_t)buf & BBMASK) ||
                    (*offset & mp->m_blockmask) ||
                    (size & mp->m_blockmask)) {
                        if (*offset >= ip->i_d.di_size) {
                                return (0);
                        }
                        return -XFS_ERROR(EINVAL);
                }
        }

        n = XFS_MAXIOFFSET(mp) - *offset;
        if ((n <= 0) || (size == 0))
                return 0;

        if (n < size)
                size = n;

        if (XFS_FORCED_SHUTDOWN(mp)) {
                return -EIO;
        }

        if (!(ioflags & IO_ISLOCKED))
                xfs_ilock(ip, XFS_IOLOCK_SHARED);

        if (DM_EVENT_ENABLED(BHV_TO_VNODE(bdp)->v_vfsp, ip, DM_EVENT_READ) &&
            !(ioflags & IO_INVIS)) {
                int error;
                vrwlock_t locktype = VRWLOCK_READ;
                int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);

                error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp), *offset, size,
                                      dmflags, &locktype);
                if (error) {
                        if (!(ioflags & IO_ISLOCKED))
                                xfs_iunlock(ip, XFS_IOLOCK_SHARED);
                        return -error;
                }
        }

        if (unlikely(ioflags & IO_ISDIRECT)) {
                xfs_rw_enter_trace(XFS_DIORD_ENTER, &ip->i_iocore,
                                        buf, size, *offset, ioflags);
                ret = (*offset < ip->i_d.di_size) ?
                        do_generic_direct_read(file, buf, size, offset) : 0;
                UPDATE_ATIME(file->f_dentry->d_inode);
        } else {
                xfs_rw_enter_trace(XFS_READ_ENTER, &ip->i_iocore,
                                        buf, size, *offset, ioflags);
                ret = generic_file_read(file, buf, size, offset);
        }

        if (!(ioflags & IO_ISLOCKED))
                xfs_iunlock(ip, XFS_IOLOCK_SHARED);

        XFS_STATS_ADD(xs_read_bytes, ret);

        if (unlikely(ioflags & IO_INVIS)) {
                /* generic_file_read updates the atime but we need to
                 * undo that because this I/O was supposed to be invisible.
                 */
                struct inode *inode = LINVFS_GET_IP(BHV_TO_VNODE(bdp));
                inode->i_atime = ip->i_d.di_atime.t_sec;
        } else {
                xfs_ichgtime(ip, XFS_ICHGTIME_ACC);
        }

        return ret;
}

/*
 * This routine is called to handle zeroing any space in the last
 * block of the file that is beyond the EOF.  We do this since the
 * size is being increased without writing anything to that block
 * and we don't want anyone to read the garbage on the disk.
 */
STATIC int                              /* error (positive) */
xfs_zero_last_block(
        struct inode    *ip,
        xfs_iocore_t    *io,
        xfs_off_t       offset,
        xfs_fsize_t     isize,
        xfs_fsize_t     end_size)
{
        xfs_fileoff_t   last_fsb;
        xfs_mount_t     *mp;
        int             nimaps;
        int             zero_offset;
        int             zero_len;
        int             isize_fsb_offset;
        int             error = 0;
        xfs_bmbt_irec_t imap;
        loff_t          loff;
        size_t          lsize;

        ASSERT(ismrlocked(io->io_lock, MR_UPDATE) != 0);
        ASSERT(offset > isize);

        mp = io->io_mount;

        isize_fsb_offset = XFS_B_FSB_OFFSET(mp, isize);
        if (isize_fsb_offset == 0) {
                /*
                 * There are no extra bytes in the last block on disk to
                 * zero, so return.
                 */
                return 0;
        }

        last_fsb = XFS_B_TO_FSBT(mp, isize);
        nimaps = 1;
        error = XFS_BMAPI(mp, NULL, io, last_fsb, 1, 0, NULL, 0, &imap,
                          &nimaps, NULL);
        if (error) {
                return error;
        }
        ASSERT(nimaps > 0);
        /*
         * If the block underlying isize is just a hole, then there
         * is nothing to zero.
         */
        if (imap.br_startblock == HOLESTARTBLOCK) {
                return 0;
        }
        /*
         * Zero the part of the last block beyond the EOF, and write it
         * out sync.  We need to drop the ilock while we do this so we
         * don't deadlock when the buffer cache calls back to us.
         */
        XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL| XFS_EXTSIZE_RD);
        loff = XFS_FSB_TO_B(mp, last_fsb);
        lsize = XFS_FSB_TO_B(mp, 1);

        zero_offset = isize_fsb_offset;
        zero_len = mp->m_sb.sb_blocksize - isize_fsb_offset;

        error = xfs_iozero(ip, loff + zero_offset, zero_len, end_size);

        XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
        ASSERT(error >= 0);
        return error;
}

/*
 * Zero any on disk space between the current EOF and the new,
 * larger EOF.  This handles the normal case of zeroing the remainder
 * of the last block in the file and the unusual case of zeroing blocks
 * out beyond the size of the file.  This second case only happens
 * with fixed size extents and when the system crashes before the inode
 * size was updated but after blocks were allocated.  If fill is set,
 * then any holes in the range are filled and zeroed.  If not, the holes
 * are left alone as holes.
 */

int                                     /* error (positive) */
xfs_zero_eof(
        vnode_t         *vp,
        xfs_iocore_t    *io,
        xfs_off_t       offset,         /* starting I/O offset */
        xfs_fsize_t     isize,          /* current inode size */
        xfs_fsize_t     end_size)       /* terminal inode size */
{
        struct inode    *ip = LINVFS_GET_IP(vp);
        xfs_fileoff_t   start_zero_fsb;
        xfs_fileoff_t   end_zero_fsb;
        xfs_fileoff_t   prev_zero_fsb;
        xfs_fileoff_t   zero_count_fsb;
        xfs_fileoff_t   last_fsb;
        xfs_extlen_t    buf_len_fsb;
        xfs_extlen_t    prev_zero_count;
        xfs_mount_t     *mp;
        int             nimaps;
        int             error = 0;
        xfs_bmbt_irec_t imap;
        loff_t          loff;
        size_t          lsize;

        ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
        ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));

        mp = io->io_mount;

        /*
         * First handle zeroing the block on which isize resides.
         * We only zero a part of that block so it is handled specially.
         */
        error = xfs_zero_last_block(ip, io, offset, isize, end_size);
        if (error) {
                ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
                ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
                return error;
        }

        /*
         * Calculate the range between the new size and the old
         * where blocks needing to be zeroed may exist.  To get the
         * block where the last byte in the file currently resides,
         * we need to subtract one from the size and truncate back
         * to a block boundary.  We subtract 1 in case the size is
         * exactly on a block boundary.
         */
        last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
        start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
        end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
        ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
        if (last_fsb == end_zero_fsb) {
                /*
                 * The size was only incremented on its last block.
                 * We took care of that above, so just return.
                 */
                return 0;
        }

        ASSERT(start_zero_fsb <= end_zero_fsb);
        prev_zero_fsb = NULLFILEOFF;
        prev_zero_count = 0;
        while (start_zero_fsb <= end_zero_fsb) {
                nimaps = 1;
                zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
                error = XFS_BMAPI(mp, NULL, io, start_zero_fsb, zero_count_fsb,
                                  0, NULL, 0, &imap, &nimaps, NULL);
                if (error) {
                        ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
                        ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
                        return error;
                }
                ASSERT(nimaps > 0);

                if (imap.br_state == XFS_EXT_UNWRITTEN ||
                    imap.br_startblock == HOLESTARTBLOCK) {
                        /*
                         * This loop handles initializing pages that were
                         * partially initialized by the code below this
                         * loop. It basically zeroes the part of the page
                         * that sits on a hole and sets the page as P_HOLE
                         * and calls remapf if it is a mapped file.
                         */
                        prev_zero_fsb = NULLFILEOFF;
                        prev_zero_count = 0;
                        start_zero_fsb = imap.br_startoff +
                                         imap.br_blockcount;
                        ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
                        continue;
                }

                /*
                 * There are blocks in the range requested.
                 * Zero them a single write at a time.  We actually
                 * don't zero the entire range returned if it is
                 * too big and simply loop around to get the rest.
                 * That is not the most efficient thing to do, but it
                 * is simple and this path should not be exercised often.
                 */
                buf_len_fsb = XFS_FILBLKS_MIN(imap.br_blockcount,
                                              mp->m_writeio_blocks << 8);
                /*
                 * Drop the inode lock while we're doing the I/O.
                 * We'll still have the iolock to protect us.
                 */
                XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);

                loff = XFS_FSB_TO_B(mp, start_zero_fsb);
                lsize = XFS_FSB_TO_B(mp, buf_len_fsb);

                error = xfs_iozero(ip, loff, lsize, end_size);

                if (error) {
                        goto out_lock;
                }

                prev_zero_fsb = start_zero_fsb;
                prev_zero_count = buf_len_fsb;
                start_zero_fsb = imap.br_startoff + buf_len_fsb;
                ASSERT(start_zero_fsb <= (end_zero_fsb + 1));

                XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
        }

        return 0;

out_lock:

        XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
        ASSERT(error >= 0);
        return error;
}

ssize_t                         /* bytes written, or (-) error */
xfs_write(
        bhv_desc_t      *bdp,
        struct file     *file,
        const char      *buf,
        size_t          size,
        loff_t          *offset,
        int             ioflags,
        cred_t          *credp)
{
        xfs_inode_t     *xip;
        xfs_mount_t     *mp;
        ssize_t         ret;
        int             error = 0;
        xfs_fsize_t     isize, new_size;
        xfs_fsize_t     n, limit;
        xfs_iocore_t    *io;
        vnode_t         *vp;
        int             iolock;
        int             eventsent = 0;
        vrwlock_t       locktype;

        XFS_STATS_INC(xs_write_calls);

        vp = BHV_TO_VNODE(bdp);
        xip = XFS_BHVTOI(bdp);

        if (size == 0)
                return 0;

        io = &xip->i_iocore;
        mp = io->io_mount;

        fs_check_frozen(vp->v_vfsp, SB_FREEZE_WRITE);

        if (XFS_FORCED_SHUTDOWN(xip->i_mount)) {
                return -EIO;
        }

        if (unlikely(ioflags & IO_ISDIRECT)) {
                if (((__psint_t)buf & BBMASK) ||
                    (*offset & mp->m_blockmask) ||
                    (size  & mp->m_blockmask)) {
                        return XFS_ERROR(-EINVAL);
                }
                iolock = XFS_IOLOCK_SHARED;
                locktype = VRWLOCK_WRITE_DIRECT;
        } else {
                iolock = XFS_IOLOCK_EXCL;
                locktype = VRWLOCK_WRITE;
        }

        if (ioflags & IO_ISLOCKED)
                iolock = 0;

        xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);

        isize = xip->i_d.di_size;
        limit = XFS_MAXIOFFSET(mp);

        if (file->f_flags & O_APPEND)
                *offset = isize;

start:
        n = limit - *offset;
        if (n <= 0) {
                xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
                return -EFBIG;
        }
        if (n < size)
                size = n;

        new_size = *offset + size;
        if (new_size > isize) {
                io->io_new_size = new_size;
        }

        if ((DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_WRITE) &&
            !(ioflags & IO_INVIS) && !eventsent)) {
                loff_t          savedsize = *offset;
                int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);

                xfs_iunlock(xip, XFS_ILOCK_EXCL);
                error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, vp,
                                      *offset, size,
                                      dmflags, &locktype);
                if (error) {
                        if (iolock) xfs_iunlock(xip, iolock);
                        return -error;
                }
                xfs_ilock(xip, XFS_ILOCK_EXCL);
                eventsent = 1;

                /*
                 * The iolock was dropped and reaquired in XFS_SEND_DATA
                 * so we have to recheck the size when appending.
                 * We will only "goto start;" once, since having sent the
                 * event prevents another call to XFS_SEND_DATA, which is
                 * what allows the size to change in the first place.
                 */
                if ((file->f_flags & O_APPEND) &&
                    savedsize != xip->i_d.di_size) {
                        *offset = isize = xip->i_d.di_size;
                        goto start;
                }
        }

        /*
         * If the offset is beyond the size of the file, we have a couple
         * of things to do. First, if there is already space allocated
         * we need to either create holes or zero the disk or ...
         *
         * If there is a page where the previous size lands, we need
         * to zero it out up to the new size.
         */

        if (!(ioflags & IO_ISDIRECT) && (*offset > isize && isize)) {
                error = xfs_zero_eof(BHV_TO_VNODE(bdp), io, *offset,
                        isize, *offset + size);
                if (error) {
                        xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
                        return(-error);
                }
        }
        xfs_iunlock(xip, XFS_ILOCK_EXCL);

        /*
         * If we're writing the file then make sure to clear the
         * setuid and setgid bits if the process is not being run
         * by root.  This keeps people from modifying setuid and
         * setgid binaries.
         */

        if (((xip->i_d.di_mode & S_ISUID) ||
            ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
                (S_ISGID | S_IXGRP))) &&
             !capable(CAP_FSETID)) {
                error = xfs_write_clear_setuid(xip);
                if (error) {
                        xfs_iunlock(xip, iolock);
                        return -error;
                }
        }


        if ((ssize_t) size < 0) {
                ret = -EINVAL;
                goto error;
        }

        if (!access_ok(VERIFY_READ, buf, size)) {
                ret = -EINVAL;
                goto error;
        }

retry:
        if (unlikely(ioflags & IO_ISDIRECT)) {
                xfs_inval_cached_pages(vp, io, *offset, 1, 1);
                xfs_rw_enter_trace(XFS_DIOWR_ENTER,
                                        io, buf, size, *offset, ioflags);
                ret = do_generic_direct_write(file, buf, size, offset);
        } else {
                xfs_rw_enter_trace(XFS_WRITE_ENTER,
                                        io, buf, size, *offset, ioflags);
                ret = do_generic_file_write(file, buf, size, offset);
        }

        if (unlikely(ioflags & IO_INVIS)) {
                /* generic_file_write updates the mtime/ctime but we need
                 * to undo that because this I/O was supposed to be
                 * invisible.
                 */
                struct inode    *inode = LINVFS_GET_IP(vp);
                inode->i_mtime = xip->i_d.di_mtime.t_sec;
                inode->i_ctime = xip->i_d.di_ctime.t_sec;
        } else {
                xfs_ichgtime(xip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        }

        if ((ret == -ENOSPC) &&
            DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_NOSPACE) &&
            !(ioflags & IO_INVIS)) {

                xfs_rwunlock(bdp, locktype);
                error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, vp,
                                DM_RIGHT_NULL, vp, DM_RIGHT_NULL, NULL, NULL,
                                0, 0, 0); /* Delay flag intentionally  unused */
                if (error)
                        return -error;
                xfs_rwlock(bdp, locktype);
                *offset = xip->i_d.di_size;
                goto retry;
        }

error:
        if (ret <= 0) {
                if (iolock)
                        xfs_rwunlock(bdp, locktype);
                return ret;
        }

        XFS_STATS_ADD(xs_write_bytes, ret);

        if (*offset > xip->i_d.di_size) {
                xfs_ilock(xip, XFS_ILOCK_EXCL);
                if (*offset > xip->i_d.di_size) {
                        struct inode    *inode = LINVFS_GET_IP(vp);

                        xip->i_d.di_size = *offset;
                        i_size_write(inode, *offset);
                        xip->i_update_core = 1;
                        xip->i_update_size = 1;
                        mark_inode_dirty_sync(inode);
                }
                xfs_iunlock(xip, XFS_ILOCK_EXCL);
        }

        /* Handle various SYNC-type writes */
        if ((file->f_flags & O_SYNC) || IS_SYNC(file->f_dentry->d_inode)) {

                /*
                 * If we're treating this as O_DSYNC and we have not updated the
                 * size, force the log.
                 */

                if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC)
                        && !(xip->i_update_size)) {
                        /*
                         * If an allocation transaction occurred
                         * without extending the size, then we have to force
                         * the log up the proper point to ensure that the
                         * allocation is permanent.  We can't count on
                         * the fact that buffered writes lock out direct I/O
                         * writes - the direct I/O write could have extended
                         * the size nontransactionally, then finished before
                         * we started.  xfs_write_file will think that the file
                         * didn't grow but the update isn't safe unless the
                         * size change is logged.
                         *
                         * Force the log if we've committed a transaction
                         * against the inode or if someone else has and
                         * the commit record hasn't gone to disk (e.g.
                         * the inode is pinned).  This guarantees that
                         * all changes affecting the inode are permanent
                         * when we return.
                         */

                        xfs_inode_log_item_t *iip;
                        xfs_lsn_t lsn;

                        iip = xip->i_itemp;
                        if (iip && iip->ili_last_lsn) {
                                lsn = iip->ili_last_lsn;
                                xfs_log_force(mp, lsn,
                                                XFS_LOG_FORCE | XFS_LOG_SYNC);
                        } else if (xfs_ipincount(xip) > 0) {
                                xfs_log_force(mp, (xfs_lsn_t)0,
                                                XFS_LOG_FORCE | XFS_LOG_SYNC);
                        }

                } else {
                        xfs_trans_t     *tp;

                        /*
                         * O_SYNC or O_DSYNC _with_ a size update are handled
                         * the same way.
                         *
                         * If the write was synchronous then we need to make
                         * sure that the inode modification time is permanent.
                         * We'll have updated the timestamp above, so here
                         * we use a synchronous transaction to log the inode.
                         * It's not fast, but it's necessary.
                         *
                         * If this a dsync write and the size got changed
                         * non-transactionally, then we need to ensure that
                         * the size change gets logged in a synchronous
                         * transaction.
                         */

                        tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
                        if ((error = xfs_trans_reserve(tp, 0,
                                                      XFS_SWRITE_LOG_RES(mp),
                                                      0, 0, 0))) {
                                /* Transaction reserve failed */
                                xfs_trans_cancel(tp, 0);
                        } else {
                                /* Transaction reserve successful */
                                xfs_ilock(xip, XFS_ILOCK_EXCL);
                                xfs_trans_ijoin(tp, xip, XFS_ILOCK_EXCL);
                                xfs_trans_ihold(tp, xip);
                                xfs_trans_log_inode(tp, xip, XFS_ILOG_CORE);
                                xfs_trans_set_sync(tp);
                                error = xfs_trans_commit(tp, 0, NULL);
                                xfs_iunlock(xip, XFS_ILOCK_EXCL);
                        }
                }
        } /* (ioflags & O_SYNC) */

        /*
         * If we are coming from an nfsd thread then insert into the
         * reference cache.
         */

        if (!strcmp(current->comm, "nfsd"))
                xfs_refcache_insert(xip);

        /* Drop lock this way - the old refcache release is in here */
        if (iolock)
                xfs_rwunlock(bdp, locktype);

        return(ret);
}

/*
 * All xfs metadata buffers except log state machine buffers
 * get this attached as their b_bdstrat callback function.
 * This is so that we can catch a buffer
 * after prematurely unpinning it to forcibly shutdown the filesystem.
 */
int
xfs_bdstrat_cb(struct xfs_buf *bp)
{
        xfs_mount_t     *mp;

        mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
        if (!XFS_FORCED_SHUTDOWN(mp)) {
                pagebuf_iorequest(bp);
                return 0;
        } else {
                xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
                /*
                 * Metadata write that didn't get logged but
                 * written delayed anyway. These aren't associated
                 * with a transaction, and can be ignored.
                 */
                if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
                    (XFS_BUF_ISREAD(bp)) == 0)
                        return (xfs_bioerror_relse(bp));
                else
                        return (xfs_bioerror(bp));
        }
}


int
xfs_bmap(bhv_desc_t     *bdp,
        xfs_off_t       offset,
        ssize_t         count,
        int             flags,
        xfs_iomap_t     *iomapp,
        int             *niomaps)
{
        xfs_inode_t     *ip = XFS_BHVTOI(bdp);
        xfs_iocore_t    *io = &ip->i_iocore;

        ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
        ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
               ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));

        return xfs_iomap(io, offset, count, flags, iomapp, niomaps);
}

/*
 * Wrapper around bdstrat so that we can stop data
 * from going to disk in case we are shutting down the filesystem.
 * Typically user data goes thru this path; one of the exceptions
 * is the superblock.
 */
int
xfsbdstrat(
        struct xfs_mount        *mp,
        struct xfs_buf          *bp)
{
        ASSERT(mp);
        if (!XFS_FORCED_SHUTDOWN(mp)) {
                /* Grio redirection would go here
                 * if (XFS_BUF_IS_GRIO(bp)) {
                 */

                pagebuf_iorequest(bp);
                return 0;
        }

        xfs_buftrace("XFSBDSTRAT IOERROR", bp);
        return (xfs_bioerror_relse(bp));
}

/*
 * If the underlying (data/log/rt) device is readonly, there are some
 * operations that cannot proceed.
 */
int
xfs_dev_is_read_only(
        xfs_mount_t             *mp,
        char                    *message)
{
        if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
            xfs_readonly_buftarg(mp->m_logdev_targp) ||
            (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
                cmn_err(CE_NOTE,
                        "XFS: %s required on read-only device.", message);
                cmn_err(CE_NOTE,
                        "XFS: write access unavailable, cannot proceed.");
                return EROFS;
        }
        return 0;
}