From 604d1b0245b97738cde4341944ad93edff4b2827 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Fri, 1 May 2015 17:49:16 +0800 Subject: 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: Yan, Zheng diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index f1dbcae..900c05f 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -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)); diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index 1a68c0e..1c991df 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -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); diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c index cd7ffad4..c6f7d9b 100644 --- a/fs/ceph/xattr.c +++ b/fs/ceph/xattr.c @@ -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; } -- cgit v0.10.2