* [PATCH v2 1/2] fsnotify: fix merge with parent's ignored mask
2022-02-23 15:14 [PATCH v2 0/2] Fsnotify ignored mask related fixes Amir Goldstein
@ 2022-02-23 15:14 ` Amir Goldstein
2022-02-23 15:14 ` [PATCH v2 2/2] fsnotify: optimize FS_MODIFY events with no ignored masks Amir Goldstein
2022-02-24 14:20 ` [PATCH v2 0/2] Fsnotify ignored mask related fixes Jan Kara
2 siblings, 0 replies; 4+ messages in thread
From: Amir Goldstein @ 2022-02-23 15:14 UTC (permalink / raw)
To: Jan Kara; +Cc: Matthew Bobrowski, linux-fsdevel
fsnotify_parent() does not consider the parent's mark at all unless
the parent inode shows interest in events on children and in the
specific event.
So unless parent added an event to both its mark mask and ignored mask,
the event will not be ignored.
Fix this by declaring the interest of an object in an event when the
event is in either a mark mask or ignored mask.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/notify/fanotify/fanotify_user.c | 17 +++++++++--------
fs/notify/mark.c | 4 ++--
include/linux/fsnotify_backend.h | 15 +++++++++++++++
3 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 2ff6bd85ba8f..bd99430a128d 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1003,17 +1003,18 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
__u32 mask, unsigned int flags,
__u32 umask, int *destroy)
{
- __u32 oldmask = 0;
+ __u32 oldmask, newmask;
/* umask bits cannot be removed by user */
mask &= ~umask;
spin_lock(&fsn_mark->lock);
+ oldmask = fsnotify_calc_mask(fsn_mark);
if (!(flags & FAN_MARK_IGNORED_MASK)) {
- oldmask = fsn_mark->mask;
fsn_mark->mask &= ~mask;
} else {
fsn_mark->ignored_mask &= ~mask;
}
+ newmask = fsnotify_calc_mask(fsn_mark);
/*
* We need to keep the mark around even if remaining mask cannot
* result in any events (e.g. mask == FAN_ONDIR) to support incremenal
@@ -1023,7 +1024,7 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
*destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask);
spin_unlock(&fsn_mark->lock);
- return mask & oldmask;
+ return oldmask & ~newmask;
}
static int fanotify_remove_mark(struct fsnotify_group *group,
@@ -1081,23 +1082,23 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
}
static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
- __u32 mask,
- unsigned int flags)
+ __u32 mask, unsigned int flags)
{
- __u32 oldmask = -1;
+ __u32 oldmask, newmask;
spin_lock(&fsn_mark->lock);
+ oldmask = fsnotify_calc_mask(fsn_mark);
if (!(flags & FAN_MARK_IGNORED_MASK)) {
- oldmask = fsn_mark->mask;
fsn_mark->mask |= mask;
} else {
fsn_mark->ignored_mask |= mask;
if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
}
+ newmask = fsnotify_calc_mask(fsn_mark);
spin_unlock(&fsn_mark->lock);
- return mask & ~oldmask;
+ return newmask & ~oldmask;
}
static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 9007d6affff3..4853184f7dde 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -127,7 +127,7 @@ static void __fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
return;
hlist_for_each_entry(mark, &conn->list, obj_list) {
if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)
- new_mask |= mark->mask;
+ new_mask |= fsnotify_calc_mask(mark);
}
*fsnotify_conn_mask_p(conn) = new_mask;
}
@@ -692,7 +692,7 @@ int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
if (ret)
goto err;
- if (mark->mask)
+ if (mark->mask || mark->ignored_mask)
fsnotify_recalc_mask(mark->connector);
return ret;
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 790c31844db5..5f9c960049b0 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -601,6 +601,21 @@ extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
/* functions used to manipulate the marks attached to inodes */
+/* Get mask for calculating object interest taking ignored mask into account */
+static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
+{
+ __u32 mask = mark->mask;
+
+ if (!mark->ignored_mask)
+ return mask;
+
+ /*
+ * If mark is interested in ignoring events on children, the object must
+ * show interest in those events for fsnotify_parent() to notice it.
+ */
+ return mask | (mark->ignored_mask & ALL_FSNOTIFY_EVENTS);
+}
+
/* Get mask of events for a list of marks */
extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
/* Calculate mask of events for a list of marks */
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v2 2/2] fsnotify: optimize FS_MODIFY events with no ignored masks
2022-02-23 15:14 [PATCH v2 0/2] Fsnotify ignored mask related fixes Amir Goldstein
2022-02-23 15:14 ` [PATCH v2 1/2] fsnotify: fix merge with parent's ignored mask Amir Goldstein
@ 2022-02-23 15:14 ` Amir Goldstein
2022-02-24 14:20 ` [PATCH v2 0/2] Fsnotify ignored mask related fixes Jan Kara
2 siblings, 0 replies; 4+ messages in thread
From: Amir Goldstein @ 2022-02-23 15:14 UTC (permalink / raw)
To: Jan Kara; +Cc: Matthew Bobrowski, linux-fsdevel
fsnotify() treats FS_MODIFY events specially - it does not skip them
even if the FS_MODIFY event does not apear in the object's fsnotify
mask. This is because send_to_group() checks if FS_MODIFY needs to
clear ignored mask of marks.
The common case is that an object does not have any mark with ignored
mask and in particular, that it does not have a mark with ignored mask
and without the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag.
Set FS_MODIFY in object's fsnotify mask during fsnotify_recalc_mask()
if object has a mark with an ignored mask and without the
FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag and remove the special
treatment of FS_MODIFY in fsnotify(), so that FS_MODIFY events could
be optimized in the common case.
Call fsnotify_recalc_mask() from fanotify after adding or removing an
ignored mask from a mark without FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY
or when adding the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag to a mark
with ignored mask (the flag cannot be removed by fanotify uapi).
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/notify/fanotify/fanotify_user.c | 32 +++++++++++++++++++++++-------
fs/notify/fsnotify.c | 8 +++++---
include/linux/fsnotify_backend.h | 4 ++++
3 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index bd99430a128d..9b32b76a9c30 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1081,8 +1081,28 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
flags, umask);
}
+static void fanotify_mark_add_ignored_mask(struct fsnotify_mark *fsn_mark,
+ __u32 mask, unsigned int flags,
+ __u32 *removed)
+{
+ fsn_mark->ignored_mask |= mask;
+
+ /*
+ * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to
+ * the removal of the FS_MODIFY bit in calculated mask if it was set
+ * because of an ignored mask that is now going to survive FS_MODIFY.
+ */
+ if ((flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
+ !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) {
+ fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
+ if (!(fsn_mark->mask & FS_MODIFY))
+ *removed = FS_MODIFY;
+ }
+}
+
static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
- __u32 mask, unsigned int flags)
+ __u32 mask, unsigned int flags,
+ __u32 *removed)
{
__u32 oldmask, newmask;
@@ -1091,9 +1111,7 @@ static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
if (!(flags & FAN_MARK_IGNORED_MASK)) {
fsn_mark->mask |= mask;
} else {
- fsn_mark->ignored_mask |= mask;
- if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
- fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
+ fanotify_mark_add_ignored_mask(fsn_mark, mask, flags, removed);
}
newmask = fsnotify_calc_mask(fsn_mark);
spin_unlock(&fsn_mark->lock);
@@ -1156,7 +1174,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
__kernel_fsid_t *fsid)
{
struct fsnotify_mark *fsn_mark;
- __u32 added;
+ __u32 added, removed = 0;
int ret = 0;
mutex_lock(&group->mark_mutex);
@@ -1179,8 +1197,8 @@ static int fanotify_add_mark(struct fsnotify_group *group,
goto out;
}
- added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
- if (added & ~fsnotify_conn_mask(fsn_mark->connector))
+ added = fanotify_mark_add_to_mask(fsn_mark, mask, flags, &removed);
+ if (removed || (added & ~fsnotify_conn_mask(fsn_mark->connector)))
fsnotify_recalc_mask(fsn_mark->connector);
out:
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index ab81a0776ece..494f653efbc6 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -531,11 +531,13 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
/*
- * if this is a modify event we may need to clear the ignored masks
- * otherwise return if none of the marks care about this type of event.
+ * If this is a modify event we may need to clear some ignored masks.
+ * In that case, the object with ignored masks will have the FS_MODIFY
+ * event in its mask.
+ * Otherwise, return if none of the marks care about this type of event.
*/
test_mask = (mask & ALL_FSNOTIFY_EVENTS);
- if (!(mask & FS_MODIFY) && !(test_mask & marks_mask))
+ if (!(test_mask & marks_mask))
return 0;
iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 5f9c960049b0..0805b74cae44 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -609,6 +609,10 @@ static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
if (!mark->ignored_mask)
return mask;
+ /* Interest in FS_MODIFY may be needed for clearing ignored mask */
+ if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
+ mask |= FS_MODIFY;
+
/*
* If mark is interested in ignoring events on children, the object must
* show interest in those events for fsnotify_parent() to notice it.
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2 0/2] Fsnotify ignored mask related fixes
2022-02-23 15:14 [PATCH v2 0/2] Fsnotify ignored mask related fixes Amir Goldstein
2022-02-23 15:14 ` [PATCH v2 1/2] fsnotify: fix merge with parent's ignored mask Amir Goldstein
2022-02-23 15:14 ` [PATCH v2 2/2] fsnotify: optimize FS_MODIFY events with no ignored masks Amir Goldstein
@ 2022-02-24 14:20 ` Jan Kara
2 siblings, 0 replies; 4+ messages in thread
From: Jan Kara @ 2022-02-24 14:20 UTC (permalink / raw)
To: Amir Goldstein; +Cc: Jan Kara, Matthew Bobrowski, linux-fsdevel
Hi Amir!
On Wed 23-02-22 17:14:36, Amir Goldstein wrote:
> The two patches are functionally unrelated, but they both incorporate
> information from the ignored mask into the object's interest mask.
>
> The 1st patch is a fix for a minor functional bug.
> LTP test fanotify10 has a workaround for this bug, see comment:
> /* XXX: temporary hack may be removed in the future */
> The test is to remove the hack and see that fanotify10 passes.
>
> The 2nd patch is a performance optimization that you suggested.
> Last time I posted it, you asked for performance numbers [1], so I ran
> some micro benchmarks (see results below [3]).
>
> Note that the other patch from that first posting ("optimize merging of
> marks with no ignored masks") did not demonstrate any visible
> improvements with the benchmarks that I ran so I left it out.
>
> The micro benchmark is a simple program [2] that writes 1 byte at a time
> in a loop. I ran it on tmpfs once without any mark and once with a mark
> with a mask for DELETE_SELF event.
>
> On upstream kernel, runtime with a mark is always ~25% longer.
> With the optimization patch applied, runtime with a mark is most of the
> time (but not always) very close to the runtime without a mark.
>
> [1] https://lore.kernel.org/linux-fsdevel/20201203145220.GH11854@quack2.suse.cz/
> [2] https://github.com/amir73il/fsnotify-utils/blob/master/src/test/ioloop.c
> [3] Performance test results:
Thanks! Both patches look good to me, I have added them to my tree (just
included shortened performance results into the changelog of the second
patch).
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 4+ messages in thread