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[PATCH 18/27] xfs: Convert to new freezing code

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: [PATCH 18/27] xfs: Convert to new freezing code
From: Jan Kara <jack@xxxxxxx>
Date: Sat, 2 Jun 2012 00:30:32 +0200
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>, dchinner@xxxxxxxxxx, Jan Kara <jack@xxxxxxx>, Ben Myers <bpm@xxxxxxx>, Alex Elder <elder@xxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <1338589841-9568-1-git-send-email-jack@xxxxxxx>
References: <1338589841-9568-1-git-send-email-jack@xxxxxxx>
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@xxxxxxx>
CC: Alex Elder <elder@xxxxxxxxxx>
CC: xfs@xxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/xfs/xfs_aops.c    |   18 ++++++++++++++++
 fs/xfs/xfs_file.c    |   10 ++++++--
 fs/xfs/xfs_ioctl.c   |   55 +++++++++++++++++++++++++++++++++++++++++++++++--
 fs/xfs/xfs_ioctl32.c |   12 ++++++++++
 fs/xfs/xfs_iomap.c   |    4 +-
 fs/xfs/xfs_mount.c   |    2 +-
 fs/xfs/xfs_mount.h   |    3 --
 fs/xfs/xfs_sync.c    |    2 +-
 fs/xfs/xfs_trans.c   |   17 ++++++++++++--
 fs/xfs/xfs_trans.h   |    2 +
 10 files changed, 109 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index ae31c31..4a001b8 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;
@@ -1405,6 +1420,9 @@ 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 8d214b8..1e7bb9c 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -778,10 +778,12 @@ 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);
@@ -800,6 +802,8 @@ 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 3a05a41..63624fb 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -361,9 +361,15 @@ 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);
@@ -379,6 +385,7 @@ 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 c4f2da0..1244274 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 aadfce6..b3b9b26 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 536021f..b09a4a7 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 8b89c5a..401ca2e 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 c9d3409..9986c7a 100644
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -392,7 +392,7 @@ xfs_sync_worker(
        if (down_read_trylock(&mp->m_super->s_umount)) {
                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 cdf896f..1639ac2 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 7ab99e1..a5d31d5 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.
-- 
1.7.1

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