src/patches/suse-2.6.27.25/patches.fixes/ocfs2-1.4-git-65bac575e35915801ea518b9d8d8824367d125c8

   1 From: Jan Kara <jack@suse.cz>
   2 Subject: ocfs2: Fix possible deadlock with quotas in ocfs2_setattr()
   3 Patch-mainline: 2.6.31
   4
   5 We called vfs_dq_transfer() with global quota file lock held. This can lead
   6 to deadlocks as if vfs_dq_transfer() has to allocate new quota structure,
   7 it calls ocfs2_dquot_acquire() which tries to get quota file lock again and
   8 this can block if another node requested the lock in the mean time.
   9
  10 Since we have to call vfs_dq_transfer() with transaction already started
  11 and quota file lock ranks above the transaction start, we cannot just rely
  12 on ocfs2_dquot_acquire() or ocfs2_dquot_release() on getting the lock
  13 if they need it. We fix the problem by acquiring pointers to all quota
  14 structures needed by vfs_dq_transfer() already before calling the function.
  15 By this we are sure that all quota structures are properly allocated and
  16 they can be freed only after we drop references to them. Thus we don't need
  17 quota file lock anywhere inside vfs_dq_transfer().
  18
  19 Signed-off-by: Jan Kara <jack@suse.cz>
  20 ---
  21  fs/ocfs2/file.c |   53 ++++++++++++++++++++++++++++++-----------------------
  22  1 files changed, 30 insertions(+), 23 deletions(-)
  23
  24 diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
  25 index c2a87c8..1a96cac 100644
  26 --- a/fs/ocfs2/file.c
  27 +++ b/fs/ocfs2/file.c
  28 @@ -894,9 +894,9 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
  29         struct ocfs2_super *osb = OCFS2_SB(sb);
  30         struct buffer_head *bh = NULL;
  31         handle_t *handle = NULL;
  32 -       int locked[MAXQUOTAS] = {0, 0};
  33 -       int credits, qtype;
  34 -       struct ocfs2_mem_dqinfo *oinfo;
  35 +       int qtype;
  36 +       struct dquot *transfer_from[MAXQUOTAS] = { };
  37 +       struct dquot *transfer_to[MAXQUOTAS] = { };
  38
  39         mlog_entry("(0x%p, '%.*s')\n", dentry,
  40                    dentry->d_name.len, dentry->d_name.name);
  41 @@ -969,30 +969,37 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
  42
  43         if ((attr->ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
  44             (attr->ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
  45 -               credits = OCFS2_INODE_UPDATE_CREDITS;
  46 +               /*
  47 +                * Gather pointers to quota structures so that allocation /
  48 +                * freeing of quota structures happens here and not inside
  49 +                * vfs_dq_transfer() where we have problems with lock ordering
  50 +                */
  51                 if (attr->ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid
  52                     && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
  53                     OCFS2_FEATURE_RO_COMPAT_USRQUOTA)) {
  54 -                       oinfo = sb_dqinfo(sb, USRQUOTA)->dqi_priv;
  55 -                       status = ocfs2_lock_global_qf(oinfo, 1);
  56 -                       if (status < 0)
  57 +                       transfer_to[USRQUOTA] = dqget(sb, attr->ia_uid,
  58 +                                                     USRQUOTA);
  59 +                       transfer_from[USRQUOTA] = dqget(sb, inode->i_uid,
  60 +                                                       USRQUOTA);
  61 +                       if (!transfer_to[USRQUOTA] || !transfer_from[USRQUOTA]) {
  62 +                               status = -ESRCH;
  63                                 goto bail_unlock;
  64 -                       credits += ocfs2_calc_qinit_credits(sb, USRQUOTA) +
  65 -                               ocfs2_calc_qdel_credits(sb, USRQUOTA);
  66 -                       locked[USRQUOTA] = 1;
  67 +                       }
  68                 }
  69                 if (attr->ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid
  70                     && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
  71                     OCFS2_FEATURE_RO_COMPAT_GRPQUOTA)) {
  72 -                       oinfo = sb_dqinfo(sb, GRPQUOTA)->dqi_priv;
  73 -                       status = ocfs2_lock_global_qf(oinfo, 1);
  74 -                       if (status < 0)
  75 +                       transfer_to[GRPQUOTA] = dqget(sb, attr->ia_gid,
  76 +                                                     GRPQUOTA);
  77 +                       transfer_from[GRPQUOTA] = dqget(sb, inode->i_gid,
  78 +                                                       GRPQUOTA);
  79 +                       if (!transfer_to[GRPQUOTA] || !transfer_from[GRPQUOTA]) {
  80 +                               status = -ESRCH;
  81                                 goto bail_unlock;
  82 -                       credits += ocfs2_calc_qinit_credits(sb, GRPQUOTA) +
  83 -                                  ocfs2_calc_qdel_credits(sb, GRPQUOTA);
  84 -                       locked[GRPQUOTA] = 1;
  85 +                       }
  86                 }
  87 -               handle = ocfs2_start_trans(osb, credits);
  88 +               handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS +
  89 +                                          2 * ocfs2_quota_trans_credits(sb));
  90                 if (IS_ERR(handle)) {
  91                         status = PTR_ERR(handle);
  92                         mlog_errno(status);
  93 @@ -1030,12 +1037,6 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
  94  bail_commit:
  95         ocfs2_commit_trans(osb, handle);
  96  bail_unlock:
  97 -       for (qtype = 0; qtype < MAXQUOTAS; qtype++) {
  98 -               if (!locked[qtype])
  99 -                       continue;
 100 -               oinfo = sb_dqinfo(sb, qtype)->dqi_priv;
 101 -               ocfs2_unlock_global_qf(oinfo, 1);
 102 -       }
 103         ocfs2_inode_unlock(inode, 1);
 104  bail_unlock_rw:
 105         if (size_change)
 106 @@ -1043,6 +1044,12 @@ bail_unlock_rw:
 107  bail:
 108         brelse(bh);
 109
 110 +       /* Release quota pointers in case we acquired them */
 111 +       for (qtype = 0; qtype < MAXQUOTAS; qtype++) {
 112 +               dqput(transfer_to[qtype]);
 113 +               dqput(transfer_from[qtype]);
 114 +       }
 115 +
 116         if (!status && attr->ia_valid & ATTR_MODE) {
 117                 status = ocfs2_acl_chmod(inode);
 118                 if (status < 0)
 119 --
 120 1.6.0.2
 121