From: Amir Goldstein <amir73il@gmail.com>
To: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v4 3/5] dnotify: move fsnotify_recalc_mask() outside spinlock
Date: Sat, 12 Nov 2022 11:06:42 +0200 [thread overview]
Message-ID: <CAOQ4uxgK6H_zaCRZG3FvUhD7-28-P79qPTTmLUD4t0XY3LakbQ@mail.gmail.com> (raw)
In-Reply-To: <20221111220614.991928-4-stephen.s.brennan@oracle.com>
On Sat, Nov 12, 2022 at 12:06 AM Stephen Brennan
<stephen.s.brennan@oracle.com> wrote:
>
> In order to allow sleeping during fsnotify_recalc_mask(), we need to
> ensure no callers are holding a spinlock.
>
> Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
small suggestion below.
> ---
> fs/notify/dnotify/dnotify.c | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
> index 190aa717fa32..a9f05b3cf5ea 100644
> --- a/fs/notify/dnotify/dnotify.c
> +++ b/fs/notify/dnotify/dnotify.c
> @@ -58,10 +58,10 @@ struct dnotify_mark {
> * dnotify cares about for that inode may change. This function runs the
> * list of everything receiving dnotify events about this directory and calculates
> * the set of all those events. After it updates what dnotify is interested in
> - * it calls the fsnotify function so it can update the set of all events relevant
> - * to this inode.
> + * it returns true if fsnotify_recalc_mask() should be called to update the set
> + * of all events related to this inode.
> */
> -static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
> +static bool dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
> {
> __u32 new_mask = 0;
> struct dnotify_struct *dn;
> @@ -74,10 +74,9 @@ static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
> for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next)
> new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT);
> if (fsn_mark->mask == new_mask)
> - return;
> + return false;
> fsn_mark->mask = new_mask;
> -
> - fsnotify_recalc_mask(fsn_mark->connector);
> + return true;
> }
>
> /*
> @@ -97,6 +96,7 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
> struct dnotify_struct **prev;
> struct fown_struct *fown;
> __u32 test_mask = mask & ~FS_EVENT_ON_CHILD;
> + bool recalc = false;
>
> /* not a dir, dnotify doesn't care */
> if (!dir && !(mask & FS_ISDIR))
> @@ -118,12 +118,15 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
> else {
> *prev = dn->dn_next;
> kmem_cache_free(dnotify_struct_cache, dn);
> - dnotify_recalc_inode_mask(inode_mark);
> + recalc = dnotify_recalc_inode_mask(inode_mark);
> }
> }
>
> spin_unlock(&inode_mark->lock);
>
> + if (recalc)
> + fsnotify_recalc_mask(inode_mark->connector);
> +
> return 0;
> }
>
> @@ -158,6 +161,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
> struct dnotify_struct **prev;
> struct inode *inode;
> bool free = false;
> + bool recalc = false;
>
> inode = file_inode(filp);
> if (!S_ISDIR(inode->i_mode))
> @@ -176,7 +180,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
> if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
> *prev = dn->dn_next;
> kmem_cache_free(dnotify_struct_cache, dn);
> - dnotify_recalc_inode_mask(fsn_mark);
> + recalc = dnotify_recalc_inode_mask(fsn_mark);
> break;
> }
> prev = &dn->dn_next;
> @@ -184,6 +188,9 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
>
> spin_unlock(&fsn_mark->lock);
>
> + if (recalc)
> + fsnotify_recalc_mask(fsn_mark->connector);
> +
> /* nothing else could have found us thanks to the dnotify_groups
> mark_mutex */
> if (dn_mark->dn == NULL) {
> @@ -268,6 +275,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
> struct file *f;
> int destroy = 0, error = 0;
> __u32 mask;
> + bool recalc = false;
>
> /* we use these to tell if we need to kfree */
> new_fsn_mark = NULL;
> @@ -377,9 +385,11 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
> else if (error == -EEXIST)
> error = 0;
>
> - dnotify_recalc_inode_mask(fsn_mark);
> + recalc = dnotify_recalc_inode_mask(fsn_mark);
> out:
> spin_unlock(&fsn_mark->lock);
> + if (recalc)
> + fsnotify_recalc_mask(fsn_mark->connector);
>
> if (destroy)
> fsnotify_detach_mark(fsn_mark);
I'd do else if (recalc)
just to emphasise that destroy and recalc are mutually exclusive.
Thanks,
Amir.
next prev parent reply other threads:[~2022-11-12 9:07 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-13 22:27 [RFC] fsnotify: allow sleepable child dentry flag update Stephen Brennan
2022-10-13 23:51 ` Al Viro
2022-11-01 21:47 ` Stephen Brennan
2022-10-14 8:01 ` Amir Goldstein
2022-10-17 7:59 ` Stephen Brennan
2022-10-17 11:44 ` Amir Goldstein
2022-10-17 16:59 ` Stephen Brennan
2022-10-17 17:42 ` Amir Goldstein
2022-10-17 9:09 ` Jan Kara
2022-10-18 4:12 ` [PATCH 0/2] fsnotify: fix softlockups iterating over d_subdirs Stephen Brennan
2022-10-18 4:12 ` [PATCH 1/2] fsnotify: Protect i_fsnotify_mask and child flags with inode rwsem Stephen Brennan
2022-10-18 7:39 ` Amir Goldstein
2022-10-21 0:33 ` Stephen Brennan
2022-10-21 7:22 ` Amir Goldstein
2022-10-18 4:12 ` [PATCH 2/2] fsnotify: allow sleepable child flag update Stephen Brennan
2022-10-18 5:36 ` Amir Goldstein
2022-10-27 7:50 ` kernel test robot
2022-10-27 8:44 ` Yujie Liu
2022-10-27 22:12 ` Stephen Brennan
2022-10-18 8:07 ` [PATCH 0/2] fsnotify: fix softlockups iterating over d_subdirs Amir Goldstein
2022-10-18 23:52 ` Stephen Brennan
2022-10-19 5:33 ` Amir Goldstein
2022-10-27 22:06 ` Stephen Brennan
2022-10-28 8:58 ` Amir Goldstein
2022-10-21 1:03 ` [PATCH v2 0/3] " Stephen Brennan
2022-10-21 1:03 ` [PATCH v2 1/3] fsnotify: Use d_find_any_alias to get dentry associated with inode Stephen Brennan
2022-10-21 9:25 ` Amir Goldstein
2022-10-21 1:03 ` [PATCH v2 2/3] fsnotify: Protect i_fsnotify_mask and child flags with inode rwsem Stephen Brennan
2022-10-21 4:01 ` kernel test robot
2022-10-21 8:22 ` Amir Goldstein
2022-10-21 9:18 ` Amir Goldstein
2022-10-25 18:02 ` Stephen Brennan
2022-10-26 5:41 ` Amir Goldstein
2022-10-21 9:17 ` Christian Brauner
2022-10-21 9:21 ` Amir Goldstein
2022-10-21 1:03 ` [PATCH v2 3/3] fsnotify: allow sleepable child flag update Stephen Brennan
2022-10-28 0:10 ` [PATCH v3 0/3] fsnotify: fix softlockups iterating over d_subdirs Stephen Brennan
2022-10-28 0:10 ` [PATCH v3 1/3] fsnotify: Use d_find_any_alias to get dentry associated with inode Stephen Brennan
2022-11-10 1:12 ` Stephen Brennan
2022-10-28 0:10 ` [PATCH v3 2/3] fsnotify: Protect i_fsnotify_mask and child flags with inode rwsem Stephen Brennan
2022-10-28 9:11 ` Amir Goldstein
2022-11-10 0:03 ` kernel test robot
2022-11-10 1:06 ` Stephen Brennan
2022-10-28 0:10 ` [PATCH v3 3/3] fsnotify: allow sleepable child flag update Stephen Brennan
2022-10-28 9:32 ` Amir Goldstein
2022-11-01 21:25 ` Stephen Brennan
2022-11-01 17:51 ` [PATCH v3 0/3] fsnotify: fix softlockups iterating over d_subdirs Jan Kara
2022-11-01 20:48 ` Stephen Brennan
2022-11-02 8:55 ` Amir Goldstein
2022-11-10 20:04 ` Stephen Brennan
2022-11-02 17:52 ` Jan Kara
2022-11-04 23:33 ` Stephen Brennan
2022-11-07 11:56 ` Jan Kara
2022-11-11 22:06 ` [PATCH v4 0/5] " Stephen Brennan
2022-11-11 22:06 ` [PATCH v4 1/5] fsnotify: clear PARENT_WATCHED flags lazily Stephen Brennan
2022-11-11 22:06 ` [PATCH v4 2/5] fsnotify: Use d_find_any_alias to get dentry associated with inode Stephen Brennan
2022-11-12 8:53 ` Amir Goldstein
2022-11-11 22:06 ` [PATCH v4 3/5] dnotify: move fsnotify_recalc_mask() outside spinlock Stephen Brennan
2022-11-12 9:06 ` Amir Goldstein [this message]
2022-11-11 22:06 ` [PATCH v4 4/5] fsnotify: allow sleepable child flag update Stephen Brennan
2022-11-12 10:00 ` Amir Goldstein
2022-11-15 7:10 ` kernel test robot
2022-11-11 22:06 ` [PATCH v4 5/5] fsnotify: require inode lock held during " Stephen Brennan
2022-11-12 9:42 ` Amir Goldstein
2022-11-11 22:08 ` [PATCH v4 0/5] fsnotify: fix softlockups iterating over d_subdirs Stephen Brennan
2022-11-22 11:50 ` Jan Kara
2022-11-22 14:03 ` Amir Goldstein
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAOQ4uxgK6H_zaCRZG3FvUhD7-28-P79qPTTmLUD4t0XY3LakbQ@mail.gmail.com \
--to=amir73il@gmail.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stephen.s.brennan@oracle.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).