xfs: Convert to new freezing code

Generic code now blocks all writers from standard write paths. So we add
blocking of all writers coming from ioctl (we get a protection of ioctl against
racing remount read-only as a bonus) and convert xfs_file_aio_write() to a
non-racy freeze protection. We also keep freeze protection on transaction
start to block internal filesystem writes such as removal of preallocated
blocks.

CC: Ben Myers <bpm@sgi.com>
CC: Alex Elder <elder@kernel.org>
CC: xfs@oss.sgi.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

10 files changed, 109 insertions, 16 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 8dad722c0041..daa42383ebd9 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -124,6 +124,12 @@ xfs_setfilesize_trans_alloc(
         ioend->io_append_trans = tp;
 
         /*
+         * We will pass freeze protection with a transaction.  So tell lockdep
+         * we released it.
+         */
+        rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
+                      1, _THIS_IP_);
+        /*
          * We hand off the transaction to the completion thread now, so
          * clear the flag here.
          */
@@ -199,6 +205,15 @@ xfs_end_io(
         struct xfs_inode *ip = XFS_I(ioend->io_inode);
         int             error = 0;
 
+        if (ioend->io_append_trans) {
+                /*
+                 * We've got freeze protection passed with the transaction.
+                 * Tell lockdep about it.
+                 */
+                rwsem_acquire_read(
+                        &ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
+                        0, 1, _THIS_IP_);
+        }
         if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
                 ioend->io_error = -EIO;
                 goto done;
@@ -1410,6 +1425,9 @@ out_trans_cancel:
         if (ioend->io_append_trans) {
                 current_set_flags_nested(&ioend->io_append_trans->t_pflags,
                                          PF_FSTRANS);
+                rwsem_acquire_read(
+                        &inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
+                        0, 1, _THIS_IP_);
                 xfs_trans_cancel(ioend->io_append_trans, 0);
         }
 out_destroy_ioend:
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 9f7ec15a6522..f0081f20e5c0 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -781,10 +781,12 @@ 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);
@@ -803,6 +805,8 @@ 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 1f1535d25a9b..0e0232c3b6d9 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -364,9 +364,15 @@ 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);
@@ -382,6 +388,7 @@ xfs_fssetdm_by_handle(
                                  fsd.fsd_dmstate);
 
  out:
+        mnt_drop_write_file(parfilp);
         dput(dentry);
         return error;
 }
@@ -634,7 +641,11 @@ 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;
 }
 
@@ -1163,6 +1174,7 @@ xfs_ioc_fssetxattr(
 {
         struct fsxattr          fa;
         unsigned int            mask;
+        int error;
 
         if (copy_from_user(&fa, arg, sizeof(fa)))
                 return -EFAULT;
@@ -1171,7 +1183,12 @@ 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
@@ -1196,6 +1213,7 @@ xfs_ioc_setxflags(
         struct fsxattr          fa;
         unsigned int            flags;
         unsigned int            mask;
+        int error;
 
         if (copy_from_user(&flags, arg, sizeof(flags)))
                 return -EFAULT;
@@ -1210,7 +1228,12 @@ 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
@@ -1385,8 +1408,13 @@ 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;
         }
 
@@ -1434,7 +1462,11 @@ 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;
         }
 
@@ -1463,9 +1495,14 @@ 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;
 
@@ -1496,7 +1533,11 @@ 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;
         }
 
@@ -1506,7 +1547,11 @@ 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;
         }
 
@@ -1516,7 +1561,11 @@ 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 c4f2da0d2bf5..1244274a5674 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -600,7 +600,11 @@ 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: {
@@ -608,7 +612,11 @@ 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
@@ -627,7 +635,11 @@ 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 aadfce6681ee..b3b9b26091a3 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -680,9 +680,9 @@ 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);
+                sb_start_intwrite(mp->m_super);
                 tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
-                tp->t_flags |= XFS_TRANS_RESERVE;
+                tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
                 error = xfs_trans_reserve(tp, resblks,
                                 XFS_WRITE_LOG_RES(mp), 0,
                                 XFS_TRANS_PERM_LOG_RES,
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 536021fb3d4e..b09a4a7eb640 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1544,7 +1544,7 @@ 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 90c1fc9eaea4..c6bca0d92cb1 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -314,9 +314,6 @@ 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 1e9ee064dbb2..0b9feacdcd1f 100644
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -394,7 +394,7 @@ xfs_sync_worker(
         if (!(mp->m_super->s_flags & MS_ACTIVE) &&
             !(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 fdf324508c5e..06ed520a767f 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -576,8 +576,12 @@ 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);
+        xfs_trans_t     *tp;
+
+        sb_start_intwrite(mp->m_super);
+        tp = _xfs_trans_alloc(mp, type, KM_SLEEP);
+        tp->t_flags |= XFS_TRANS_FREEZE_PROT;
+        return tp;
 }
 
 xfs_trans_t *
@@ -588,6 +592,7 @@ _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);
@@ -611,6 +616,8 @@ xfs_trans_free(
         xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false);
 
         atomic_dec(&tp->t_mountp->m_active_trans);
+        if (tp->t_flags & XFS_TRANS_FREEZE_PROT)
+                sb_end_intwrite(tp->t_mountp->m_super);
         xfs_trans_free_dqinfo(tp);
         kmem_zone_free(xfs_trans_zone, tp);
 }
@@ -643,7 +650,11 @@ xfs_trans_dup(
         ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
         ASSERT(tp->t_ticket != NULL);
 
-        ntp->t_flags = XFS_TRANS_PERM_LOG_RES | (tp->t_flags & XFS_TRANS_RESERVE);
+        ntp->t_flags = XFS_TRANS_PERM_LOG_RES |
+                       (tp->t_flags & XFS_TRANS_RESERVE) |
+                       (tp->t_flags & XFS_TRANS_FREEZE_PROT);
+        /* We gave our writer reference to the new transaction */
+        tp->t_flags &= ~XFS_TRANS_FREEZE_PROT;
         ntp->t_ticket = xfs_log_ticket_get(tp->t_ticket);
         ntp->t_blk_res = tp->t_blk_res - tp->t_blk_res_used;
         tp->t_blk_res = tp->t_blk_res_used;
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 7c37b533aa8e..19c174282878 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -179,6 +179,8 @@ struct xfs_log_item_desc {
 #define XFS_TRANS_SYNC          0x08    /* make commit synchronous */
 #define XFS_TRANS_DQ_DIRTY      0x10    /* at least one dquot in trx dirty */
 #define XFS_TRANS_RESERVE       0x20    /* OK to use reserved data blocks */
+#define XFS_TRANS_FREEZE_PROT   0x40    /* Transaction has elevated writer
+                                           count in superblock */
 
 /*
  * Values for call flags parameter.