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[PATCH 11/19] xfs: Convert to new freezing code

To: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Subject: [PATCH 11/19] xfs: Convert to new freezing code
From: Jan Kara <jack@xxxxxxx>
Date: Mon, 5 Mar 2012 17:01:09 +0100
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, Al Viro <viro@xxxxxxxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, dchinner@xxxxxxxxxx, sandeen@xxxxxxxxxx, Kamal Mostafa <kamal@xxxxxxxxxxxxx>, Jan Kara <jack@xxxxxxx>, Ben Myers <bpm@xxxxxxx>, Alex Elder <elder@xxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <1330963277-26336-1-git-send-email-jack@xxxxxxx>
References: <1330963277-26336-1-git-send-email-jack@xxxxxxx>
Generic code now blocks all writers from standard write paths. So we block all
writers coming from ioctl and replace blocking of transactions on frozen
filesystem with a debugging check. As a bonus, we get a protection of ioctl
against racing remount read-only. We also convert xfs_file_aio_write() to a
non-racy freeze protection.

CC: Ben Myers <bpm@xxxxxxx>
CC: Alex Elder <elder@xxxxxxxxxx>
CC: xfs@xxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/xfs/xfs_file.c    |   10 ++++++--
 fs/xfs/xfs_ioctl.c   |   55 +++++++++++++++++++++++++++++++++++++++++++++++--
 fs/xfs/xfs_ioctl32.c |   12 ++++++++++
 fs/xfs/xfs_iomap.c   |    1 -
 fs/xfs/xfs_mount.c   |    2 +-
 fs/xfs/xfs_mount.h   |    3 --
 fs/xfs/xfs_sync.c    |    2 +-
 fs/xfs/xfs_trans.c   |    2 +-
 8 files changed, 74 insertions(+), 13 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 7e5bc87..57dd20e 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -874,10 +874,12 @@ xfs_file_aio_write(
        if (ocount == 0)
                return 0;
 
-       xfs_wait_for_freeze(ip->i_mount, SB_FREEZE_WRITE);
+       sb_start_write(inode->i_sb);
 
-       if (XFS_FORCED_SHUTDOWN(ip->i_mount))
-               return -EIO;
+       if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+               ret = -EIO;
+               goto out;
+       }
 
        if (unlikely(file->f_flags & O_DIRECT))
                ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos, ocount);
@@ -896,6 +898,8 @@ xfs_file_aio_write(
                        ret = err;
        }
 
+out:
+       sb_end_write(inode->i_sb);
        return ret;
 }
 
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 76f3ca5..7890105 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -367,9 +367,15 @@ xfs_fssetdm_by_handle(
        if (copy_from_user(&dmhreq, arg, sizeof(xfs_fsop_setdm_handlereq_t)))
                return -XFS_ERROR(EFAULT);
 
+       error = mnt_want_write_file(parfilp);
+       if (error)
+               return error;
+
        dentry = xfs_handlereq_to_dentry(parfilp, &dmhreq.hreq);
-       if (IS_ERR(dentry))
+       if (IS_ERR(dentry)) {
+               mnt_drop_write_file(parfilp);
                return PTR_ERR(dentry);
+       }
 
        if (IS_IMMUTABLE(dentry->d_inode) || IS_APPEND(dentry->d_inode)) {
                error = -XFS_ERROR(EPERM);
@@ -385,6 +391,7 @@ xfs_fssetdm_by_handle(
                                 fsd.fsd_dmstate);
 
  out:
+       mnt_drop_write_file(parfilp);
        dput(dentry);
        return error;
 }
@@ -631,7 +638,11 @@ xfs_ioc_space(
        if (ioflags & IO_INVIS)
                attr_flags |= XFS_ATTR_DMI;
 
+       error = mnt_want_write_file(filp);
+       if (error)
+               return error;
        error = xfs_change_file_space(ip, cmd, bf, filp->f_pos, attr_flags);
+       mnt_drop_write_file(filp);
        return -error;
 }
 
@@ -1160,6 +1171,7 @@ xfs_ioc_fssetxattr(
 {
        struct fsxattr          fa;
        unsigned int            mask;
+       int error;
 
        if (copy_from_user(&fa, arg, sizeof(fa)))
                return -EFAULT;
@@ -1168,7 +1180,12 @@ xfs_ioc_fssetxattr(
        if (filp->f_flags & (O_NDELAY|O_NONBLOCK))
                mask |= FSX_NONBLOCK;
 
-       return -xfs_ioctl_setattr(ip, &fa, mask);
+       error = mnt_want_write_file(filp);
+       if (error)
+               return error;
+       error = xfs_ioctl_setattr(ip, &fa, mask);
+       mnt_drop_write_file(filp);
+       return -error;
 }
 
 STATIC int
@@ -1193,6 +1210,7 @@ xfs_ioc_setxflags(
        struct fsxattr          fa;
        unsigned int            flags;
        unsigned int            mask;
+       int error;
 
        if (copy_from_user(&flags, arg, sizeof(flags)))
                return -EFAULT;
@@ -1207,7 +1225,12 @@ xfs_ioc_setxflags(
                mask |= FSX_NONBLOCK;
        fa.fsx_xflags = xfs_merge_ioc_xflags(flags, xfs_ip2xflags(ip));
 
-       return -xfs_ioctl_setattr(ip, &fa, mask);
+       error = mnt_want_write_file(filp);
+       if (error)
+               return error;
+       error = xfs_ioctl_setattr(ip, &fa, mask);
+       mnt_drop_write_file(filp);
+       return -error;
 }
 
 STATIC int
@@ -1382,8 +1405,13 @@ xfs_file_ioctl(
                if (copy_from_user(&dmi, arg, sizeof(dmi)))
                        return -XFS_ERROR(EFAULT);
 
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
+
                error = xfs_set_dmattrs(ip, dmi.fsd_dmevmask,
                                dmi.fsd_dmstate);
+               mnt_drop_write_file(filp);
                return -error;
        }
 
@@ -1431,7 +1459,11 @@ xfs_file_ioctl(
 
                if (copy_from_user(&sxp, arg, sizeof(xfs_swapext_t)))
                        return -XFS_ERROR(EFAULT);
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_swapext(&sxp);
+               mnt_drop_write_file(filp);
                return -error;
        }
 
@@ -1460,9 +1492,14 @@ xfs_file_ioctl(
                if (copy_from_user(&inout, arg, sizeof(inout)))
                        return -XFS_ERROR(EFAULT);
 
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
+
                /* input parameter is passed in resblks field of structure */
                in = inout.resblks;
                error = xfs_reserve_blocks(mp, &in, &inout);
+               mnt_drop_write_file(filp);
                if (error)
                        return -error;
 
@@ -1493,7 +1530,11 @@ xfs_file_ioctl(
                if (copy_from_user(&in, arg, sizeof(in)))
                        return -XFS_ERROR(EFAULT);
 
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_growfs_data(mp, &in);
+               mnt_drop_write_file(filp);
                return -error;
        }
 
@@ -1503,7 +1544,11 @@ xfs_file_ioctl(
                if (copy_from_user(&in, arg, sizeof(in)))
                        return -XFS_ERROR(EFAULT);
 
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_growfs_log(mp, &in);
+               mnt_drop_write_file(filp);
                return -error;
        }
 
@@ -1513,7 +1558,11 @@ xfs_file_ioctl(
                if (copy_from_user(&in, arg, sizeof(in)))
                        return -XFS_ERROR(EFAULT);
 
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_growfs_rt(mp, &in);
+               mnt_drop_write_file(filp);
                return -error;
        }
 
diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index f9ccb7b..2012369 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -602,7 +602,11 @@ xfs_file_compat_ioctl(
 
                if (xfs_compat_growfs_data_copyin(&in, arg))
                        return -XFS_ERROR(EFAULT);
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_growfs_data(mp, &in);
+               mnt_drop_write_file(filp);
                return -error;
        }
        case XFS_IOC_FSGROWFSRT_32: {
@@ -610,7 +614,11 @@ xfs_file_compat_ioctl(
 
                if (xfs_compat_growfs_rt_copyin(&in, arg))
                        return -XFS_ERROR(EFAULT);
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_growfs_rt(mp, &in);
+               mnt_drop_write_file(filp);
                return -error;
        }
 #endif
@@ -629,7 +637,11 @@ xfs_file_compat_ioctl(
                                   offsetof(struct xfs_swapext, sx_stat)) ||
                    xfs_ioctl32_bstat_copyin(&sxp.sx_stat, &sxu->sx_stat))
                        return -XFS_ERROR(EFAULT);
+               error = mnt_want_write_file(filp);
+               if (error)
+                       return error;
                error = xfs_swapext(&sxp);
+               mnt_drop_write_file(filp);
                return -error;
        }
        case XFS_IOC_FSBULKSTAT_32:
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 246c7d5..7ab98d9 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -679,7 +679,6 @@ xfs_iomap_write_unwritten(
                 * the same inode that we complete here and might deadlock
                 * on the iolock.
                 */
-               xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
                tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
                tp->t_flags |= XFS_TRANS_RESERVE;
                error = xfs_trans_reserve(tp, resblks,
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index d06afbc..bead529 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1541,7 +1541,7 @@ xfs_unmountfs(
 int
 xfs_fs_writable(xfs_mount_t *mp)
 {
-       return !(xfs_test_for_freeze(mp) || XFS_FORCED_SHUTDOWN(mp) ||
+       return !(mp->m_super->s_writers.frozen || XFS_FORCED_SHUTDOWN(mp) ||
                (mp->m_flags & XFS_MOUNT_RDONLY));
 }
 
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 19f69e2..f0afeb9 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -310,9 +310,6 @@ void xfs_do_force_shutdown(struct xfs_mount *mp, int flags, 
char *fname,
 #define SHUTDOWN_REMOTE_REQ    0x0010  /* shutdown came from remote cell */
 #define SHUTDOWN_DEVICE_REQ    0x0020  /* failed all paths to the device */
 
-#define xfs_test_for_freeze(mp)                ((mp)->m_super->s_frozen)
-#define xfs_wait_for_freeze(mp,l)      vfs_check_frozen((mp)->m_super, (l))
-
 /*
  * Flags for xfs_mountfs
  */
diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c
index 40b75ee..c44d687 100644
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -498,7 +498,7 @@ xfs_sync_worker(
 
        if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
                /* dgc: errors ignored here */
-               if (mp->m_super->s_frozen == SB_UNFROZEN &&
+               if (mp->m_super->s_writers.frozen == SB_UNFROZEN &&
                    xfs_log_need_covered(mp))
                        error = xfs_fs_log_dummy(mp);
                else
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 329b06a..6468a2a 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -577,7 +577,6 @@ xfs_trans_alloc(
        xfs_mount_t     *mp,
        uint            type)
 {
-       xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
        return _xfs_trans_alloc(mp, type, KM_SLEEP);
 }
 
@@ -589,6 +588,7 @@ _xfs_trans_alloc(
 {
        xfs_trans_t     *tp;
 
+       WARN_ON(mp->m_super->s_writers.frozen == SB_FREEZE_COMPLETE);
        atomic_inc(&mp->m_active_trans);
 
        tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
-- 
1.7.1

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