Commit 604d1b02 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: take snap_rwsem when accessing snap realm's cached_context 



When ceph inode's i_head_snapc is NULL, __ceph_mark_dirty_caps()
accesses snap realm's cached_context. So we need take read lock
of snap_rwsem.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 86056090

fs/ceph/caps.c

+3 −1
Original line number Diff line number Diff line
@@ -1413,9 +1413,11 @@ int __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask) 
	     ceph_cap_string(was | mask));

	ci->i_dirty_caps |= mask;

	if (was == 0) {

		if (!ci->i_head_snapc)

		if (!ci->i_head_snapc) {

			WARN_ON_ONCE(!rwsem_is_locked(&mdsc->snap_rwsem));

			ci->i_head_snapc = ceph_get_snap_context(

				ci->i_snap_realm->cached_context);

		}

		dout(" inode %p now dirty snapc %p auth cap %p\n",

		     &ci->vfs_inode, ci->i_head_snapc, ci->i_auth_cap);

		BUG_ON(!list_empty(&ci->i_dirty_item));

fs/ceph/inode.c

+15 −0
Original line number Diff line number Diff line
@@ -1727,6 +1727,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr) 
	int mask = 0;

	int err = 0;

	int inode_dirty_flags = 0;

	bool lock_snap_rwsem = false;



	if (ceph_snap(inode) != CEPH_NOSNAP)

		return -EROFS;
@@ -1742,6 +1743,18 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr) 


	spin_lock(&ci->i_ceph_lock);

	issued = __ceph_caps_issued(ci, NULL);



	if (!ci->i_head_snapc &&

	    (issued & (CEPH_CAP_ANY_EXCL | CEPH_CAP_FILE_WR))) {

		lock_snap_rwsem = true;

		if (!down_read_trylock(&mdsc->snap_rwsem)) {

			spin_unlock(&ci->i_ceph_lock);

			down_read(&mdsc->snap_rwsem);

			spin_lock(&ci->i_ceph_lock);

			issued = __ceph_caps_issued(ci, NULL);

		}

	}



	dout("setattr %p issued %s\n", inode, ceph_cap_string(issued));



	if (ia_valid & ATTR_UID) {
@@ -1890,6 +1903,8 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr) 


	release &= issued;

	spin_unlock(&ci->i_ceph_lock);

	if (lock_snap_rwsem)

		up_read(&mdsc->snap_rwsem);



	if (inode_dirty_flags)

		__mark_inode_dirty(inode, inode_dirty_flags);

fs/ceph/xattr.c

+39 −6
Original line number Diff line number Diff line
@@ -911,6 +911,7 @@ int __ceph_setxattr(struct dentry *dentry, const char *name, 
	struct inode *inode = d_inode(dentry);

	struct ceph_vxattr *vxattr;

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_mds_client *mdsc = ceph_sb_to_client(dentry->d_sb)->mdsc;

	int issued;

	int err;

	int dirty = 0;
@@ -920,6 +921,7 @@ int __ceph_setxattr(struct dentry *dentry, const char *name, 
	char *newval = NULL;

	struct ceph_inode_xattr *xattr = NULL;

	int required_blob_size;

	bool lock_snap_rwsem = false;



	if (!ceph_is_valid_xattr(name))

		return -EOPNOTSUPP;
@@ -951,9 +953,20 @@ int __ceph_setxattr(struct dentry *dentry, const char *name, 
	spin_lock(&ci->i_ceph_lock);

retry:

	issued = __ceph_caps_issued(ci, NULL);

	dout("setxattr %p issued %s\n", inode, ceph_cap_string(issued));

	if (ci->i_xattrs.version == 0 || !(issued & CEPH_CAP_XATTR_EXCL))

		goto do_sync;



	if (!lock_snap_rwsem && !ci->i_head_snapc) {

		lock_snap_rwsem = true;

		if (!down_read_trylock(&mdsc->snap_rwsem)) {

			spin_unlock(&ci->i_ceph_lock);

			down_read(&mdsc->snap_rwsem);

			spin_lock(&ci->i_ceph_lock);

			goto retry;

		}

	}



	dout("setxattr %p issued %s\n", inode, ceph_cap_string(issued));

	__build_xattrs(inode);



	required_blob_size = __get_required_blob_size(ci, name_len, val_len);
@@ -966,7 +979,7 @@ retry: 
		dout(" preaallocating new blob size=%d\n", required_blob_size);

		blob = ceph_buffer_new(required_blob_size, GFP_NOFS);

		if (!blob)

			goto out;

			goto do_sync_unlocked;

		spin_lock(&ci->i_ceph_lock);

		if (ci->i_xattrs.prealloc_blob)

			ceph_buffer_put(ci->i_xattrs.prealloc_blob);
@@ -984,6 +997,8 @@ retry: 
	}



	spin_unlock(&ci->i_ceph_lock);

	if (lock_snap_rwsem)

		up_read(&mdsc->snap_rwsem);

	if (dirty)

		__mark_inode_dirty(inode, dirty);

	return err;
@@ -991,6 +1006,8 @@ retry: 
do_sync:

	spin_unlock(&ci->i_ceph_lock);

do_sync_unlocked:

	if (lock_snap_rwsem)

		up_read(&mdsc->snap_rwsem);

	err = ceph_sync_setxattr(dentry, name, value, size, flags);

out:

	kfree(newname);
@@ -1044,10 +1061,12 @@ int __ceph_removexattr(struct dentry *dentry, const char *name) 
	struct inode *inode = d_inode(dentry);

	struct ceph_vxattr *vxattr;

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_mds_client *mdsc = ceph_sb_to_client(dentry->d_sb)->mdsc;

	int issued;

	int err;

	int required_blob_size;

	int dirty;

	bool lock_snap_rwsem = false;



	if (!ceph_is_valid_xattr(name))

		return -EOPNOTSUPP;
@@ -1064,10 +1083,21 @@ int __ceph_removexattr(struct dentry *dentry, const char *name) 
	spin_lock(&ci->i_ceph_lock);

retry:

	issued = __ceph_caps_issued(ci, NULL);

	dout("removexattr %p issued %s\n", inode, ceph_cap_string(issued));



	if (ci->i_xattrs.version == 0 || !(issued & CEPH_CAP_XATTR_EXCL))

		goto do_sync;



	if (!lock_snap_rwsem && !ci->i_head_snapc) {

		lock_snap_rwsem = true;

		if (!down_read_trylock(&mdsc->snap_rwsem)) {

			spin_unlock(&ci->i_ceph_lock);

			down_read(&mdsc->snap_rwsem);

			spin_lock(&ci->i_ceph_lock);

			goto retry;

		}

	}



	dout("removexattr %p issued %s\n", inode, ceph_cap_string(issued));



	__build_xattrs(inode);



	required_blob_size = __get_required_blob_size(ci, 0, 0);
@@ -1080,7 +1110,7 @@ retry: 
		dout(" preaallocating new blob size=%d\n", required_blob_size);

		blob = ceph_buffer_new(required_blob_size, GFP_NOFS);

		if (!blob)

			goto out;

			goto do_sync_unlocked;

		spin_lock(&ci->i_ceph_lock);

		if (ci->i_xattrs.prealloc_blob)

			ceph_buffer_put(ci->i_xattrs.prealloc_blob);
@@ -1094,14 +1124,17 @@ retry: 
	ci->i_xattrs.dirty = true;

	inode->i_ctime = CURRENT_TIME;

	spin_unlock(&ci->i_ceph_lock);

	if (lock_snap_rwsem)

		up_read(&mdsc->snap_rwsem);

	if (dirty)

		__mark_inode_dirty(inode, dirty);

	return err;

do_sync:

	spin_unlock(&ci->i_ceph_lock);

do_sync_unlocked:

	if (lock_snap_rwsem)

		up_read(&mdsc->snap_rwsem);

	err = ceph_send_removexattr(dentry, name);

out:

	return err;

}

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