Commit 37505d57 authored by Yan, Zheng's avatar Yan, Zheng Committed by Sage Weil
Browse files

ceph: take i_mutex before getting Fw cap 



There is deadlock as illustrated bellow. The fix is taking i_mutex
before getting Fw cap reference.

      write                    truncate                 MDS
---------------------     --------------------      --------------
get Fw cap
                          lock i_mutex
lock i_mutex (blocked)
                          request setattr.size  ->
                                                <-   revoke Fw cap

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 26be8808

fs/ceph/caps.c

+7 −6
Original line number Diff line number Diff line
@@ -2052,6 +2052,13 @@ static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want, 
		goto out;

	}



	/* finish pending truncate */

	while (ci->i_truncate_pending) {

		spin_unlock(&ci->i_ceph_lock);

		__ceph_do_pending_vmtruncate(inode, !(need & CEPH_CAP_FILE_WR));

		spin_lock(&ci->i_ceph_lock);

	}



	if (need & CEPH_CAP_FILE_WR) {

		if (endoff >= 0 && endoff > (loff_t)ci->i_max_size) {

			dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
@@ -2073,12 +2080,6 @@ static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want, 
	}

	have = __ceph_caps_issued(ci, &implemented);



	/*

	 * disallow writes while a truncate is pending

	 */

	if (ci->i_truncate_pending)

		have &= ~CEPH_CAP_FILE_WR;



	if ((have & need) == need) {

		/*

		 * Look at (implemented & ~have & not) so that we keep waiting

fs/ceph/file.c

+6 −6
Original line number Diff line number Diff line
@@ -651,7 +651,6 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov, 
	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",

	     inode, ceph_vinop(inode), pos, (unsigned)len, inode);

again:

	__ceph_do_pending_vmtruncate(inode, true);

	if (fi->fmode & CEPH_FILE_MODE_LAZY)

		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;

	else
@@ -728,7 +727,7 @@ retry_snap: 
		ret = -ENOSPC;

		goto out;

	}

	__ceph_do_pending_vmtruncate(inode, true);

	mutex_lock(&inode->i_mutex);

	dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu\n",

	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,

	     inode->i_size);
@@ -737,8 +736,10 @@ retry_snap: 
	else

		want = CEPH_CAP_FILE_BUFFER;

	ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, endoff);

	if (ret < 0)

		goto out_put;

	if (ret < 0) {

		mutex_unlock(&inode->i_mutex);

		goto out;

	}



	dout("aio_write %p %llx.%llx %llu~%u  got cap refs on %s\n",

	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
@@ -748,10 +749,10 @@ retry_snap: 
	    (iocb->ki_filp->f_flags & O_DIRECT) ||

	    (inode->i_sb->s_flags & MS_SYNCHRONOUS) ||

	    (fi->flags & CEPH_F_SYNC)) {

		mutex_unlock(&inode->i_mutex);

		ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,

			&iocb->ki_pos);

	} else {

		mutex_lock(&inode->i_mutex);

		ret = __generic_file_aio_write(iocb, iov, nr_segs,

					       &iocb->ki_pos);

		mutex_unlock(&inode->i_mutex);
@@ -766,7 +767,6 @@ retry_snap: 
			__mark_inode_dirty(inode, dirty);

	}



out_put:

	dout("aio_write %p %llx.%llx %llu~%u  dropping cap refs on %s\n",

	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,

	     ceph_cap_string(got));

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