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fanotify: cache fsid in fsnotify_mark_connector

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For FAN_REPORT_FID, we need to encode fid with fsid of the filesystem on
every event. To avoid having to call vfs_statfs() on every event to get
fsid, we store the fsid in fsnotify_mark_connector on the first time we
add a mark and on handle event we use the cached fsid.

Subsequent calls to add mark on the same object are expected to pass the
same fsid, so the call will fail on cached fsid mismatch.

If an event is reported on several mark types (inode, mount, filesystem),
all connectors should already have the same fsid, so we use the cached
fsid from the first connector.

[JK: Simplify code flow around fanotify_get_fid()
     make fsid argument of fsnotify_add_mark_locked() unconditional]

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein
2019-01-10 19:04:37 +02:00
committed by Jan Kara
parent a8b13aa20a
commit 77115225ac
5 changed files with 128 additions and 58 deletions
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62
fs/notify/fanotify/fanotify_user.c
View File

@@ -653,7 +653,8 @@ static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
fsnotify_connp_t *connp,
unsigned int type)
unsigned int type,
__kernel_fsid_t *fsid)
{
struct fsnotify_mark *mark;
int ret;
@@ -666,7 +667,7 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
return ERR_PTR(-ENOMEM);
fsnotify_init_mark(mark, group);
ret = fsnotify_add_mark_locked(mark, connp, type, 0);
ret = fsnotify_add_mark_locked(mark, connp, type, 0, fsid);
if (ret) {
fsnotify_put_mark(mark);
return ERR_PTR(ret);
@@ -678,7 +679,8 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
static int fanotify_add_mark(struct fsnotify_group *group,
fsnotify_connp_t *connp, unsigned int type,
__u32 mask, unsigned int flags)
__u32 mask, unsigned int flags,
__kernel_fsid_t *fsid)
{
struct fsnotify_mark *fsn_mark;
__u32 added;
@@ -686,7 +688,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
mutex_lock(&group->mark_mutex);
fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) {
fsn_mark = fanotify_add_new_mark(group, connp, type);
fsn_mark = fanotify_add_new_mark(group, connp, type, fsid);
if (IS_ERR(fsn_mark)) {
mutex_unlock(&group->mark_mutex);
return PTR_ERR(fsn_mark);
@@ -703,23 +705,23 @@ static int fanotify_add_mark(struct fsnotify_group *group,
static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
struct vfsmount *mnt, __u32 mask,
unsigned int flags)
unsigned int flags, __kernel_fsid_t *fsid)
{
return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks,
FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags);
FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid);
}
static int fanotify_add_sb_mark(struct fsnotify_group *group,
struct super_block *sb, __u32 mask,
unsigned int flags)
struct super_block *sb, __u32 mask,
unsigned int flags, __kernel_fsid_t *fsid)
{
return fanotify_add_mark(group, &sb->s_fsnotify_marks,
FSNOTIFY_OBJ_TYPE_SB, mask, flags);
FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid);
}
static int fanotify_add_inode_mark(struct fsnotify_group *group,
struct inode *inode, __u32 mask,
unsigned int flags)
unsigned int flags, __kernel_fsid_t *fsid)
{
pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
@@ -734,7 +736,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
return 0;
return fanotify_add_mark(group, &inode->i_fsnotify_marks,
FSNOTIFY_OBJ_TYPE_INODE, mask, flags);
FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid);
}
/* fanotify syscalls */
@@ -798,7 +800,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
atomic_inc(&user->fanotify_listeners);
group->memcg = get_mem_cgroup_from_mm(current->mm);
oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL);
oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL, NULL);
if (unlikely(!oevent)) {
fd = -ENOMEM;
goto out_destroy_group;
@@ -861,9 +863,9 @@ out_destroy_group:
}
/* Check if filesystem can encode a unique fid */
static int fanotify_test_fid(struct path *path)
static int fanotify_test_fid(struct path *path, struct kstatfs *stat)
{
struct kstatfs stat, root_stat;
struct kstatfs root_stat;
struct path root = {
.mnt = path->mnt,
.dentry = path->dentry->d_sb->s_root,
@@ -873,11 +875,11 @@ static int fanotify_test_fid(struct path *path)
/*
* Make sure path is not in filesystem with zero fsid (e.g. tmpfs).
*/
err = vfs_statfs(path, &stat);
err = vfs_statfs(path, stat);
if (err)
return err;
if (!stat.f_fsid.val[0] && !stat.f_fsid.val[1])
if (!stat->f_fsid.val[0] && !stat->f_fsid.val[1])
return -ENODEV;
/*
@@ -888,8 +890,8 @@ static int fanotify_test_fid(struct path *path)
if (err)
return err;
if (root_stat.f_fsid.val[0] != stat.f_fsid.val[0] ||
root_stat.f_fsid.val[1] != stat.f_fsid.val[1])
if (root_stat.f_fsid.val[0] != stat->f_fsid.val[0] ||
root_stat.f_fsid.val[1] != stat->f_fsid.val[1])
return -EXDEV;
/*
@@ -914,6 +916,8 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
struct fsnotify_group *group;
struct fd f;
struct path path;
struct kstatfs stat;
__kernel_fsid_t *fsid = NULL;
u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
int ret;
@@ -992,9 +996,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
goto fput_and_out;
if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
ret = fanotify_test_fid(&path);
ret = fanotify_test_fid(&path, &stat);
if (ret)
goto path_put_and_out;
fsid = &stat.f_fsid;
}
/* inode held in place by reference to path; group by fget on fd */
@@ -1007,19 +1013,25 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
case FAN_MARK_ADD:
if (mark_type == FAN_MARK_MOUNT)
ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
ret = fanotify_add_vfsmount_mark(group, mnt, mask,
flags, fsid);
else if (mark_type == FAN_MARK_FILESYSTEM)
ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, flags);
ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask,
flags, fsid);
else
ret = fanotify_add_inode_mark(group, inode, mask, flags);
ret = fanotify_add_inode_mark(group, inode, mask,
flags, fsid);
break;
case FAN_MARK_REMOVE:
if (mark_type == FAN_MARK_MOUNT)
ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
ret = fanotify_remove_vfsmount_mark(group, mnt, mask,
flags);
else if (mark_type == FAN_MARK_FILESYSTEM)
ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, flags);
ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask,
flags);
else
ret = fanotify_remove_inode_mark(group, inode, mask, flags);
ret = fanotify_remove_inode_mark(group, inode, mask,
flags);
break;
default:
ret = -EINVAL;