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Date: Tue, 19 Oct 2021 08:56:32 +0300
From: Amir Goldstein <amir73il@...il.com>
To: Gabriel Krisman Bertazi <krisman@...labora.com>
Cc: Jan Kara <jack@...e.com>, "Darrick J. Wong" <djwong@...nel.org>,
Theodore Tso <tytso@....edu>,
Dave Chinner <david@...morbit.com>,
David Howells <dhowells@...hat.com>,
Khazhismel Kumykov <khazhy@...gle.com>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
Ext4 <linux-ext4@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>, kernel@...labora.com
Subject: Re: [PATCH v8 22/32] fanotify: Support merging of error events
On Tue, Oct 19, 2021 at 3:03 AM Gabriel Krisman Bertazi
<krisman@...labora.com> wrote:
>
> Error events (FAN_FS_ERROR) against the same file system can be merged
> by simply iterating the error count. The hash is taken from the fsid,
> without considering the FH. This means that only the first error object
> is reported.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
>
Reviewed-by: Amir Goldstein <amir73il@...il.com>
> ---
> Changes since v7:
> - Move fee->fsid assignment here (Amir)
> - Open code error event merge logic in fanotify_merge (Jan)
> ---
> fs/notify/fanotify/fanotify.c | 26 ++++++++++++++++++++++++--
> fs/notify/fanotify/fanotify.h | 4 +++-
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 1f195c95dfcd..cedcb1546804 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -111,6 +111,16 @@ static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
> return fanotify_info_equal(info1, info2);
> }
>
> +static bool fanotify_error_event_equal(struct fanotify_error_event *fee1,
> + struct fanotify_error_event *fee2)
> +{
> + /* Error events against the same file system are always merged. */
> + if (!fanotify_fsid_equal(&fee1->fsid, &fee2->fsid))
> + return false;
> +
> + return true;
> +}
> +
> static bool fanotify_should_merge(struct fanotify_event *old,
> struct fanotify_event *new)
> {
> @@ -141,6 +151,9 @@ static bool fanotify_should_merge(struct fanotify_event *old,
> case FANOTIFY_EVENT_TYPE_FID_NAME:
> return fanotify_name_event_equal(FANOTIFY_NE(old),
> FANOTIFY_NE(new));
> + case FANOTIFY_EVENT_TYPE_FS_ERROR:
> + return fanotify_error_event_equal(FANOTIFY_EE(old),
> + FANOTIFY_EE(new));
> default:
> WARN_ON_ONCE(1);
> }
> @@ -176,6 +189,10 @@ static int fanotify_merge(struct fsnotify_group *group,
> break;
> if (fanotify_should_merge(old, new)) {
> old->mask |= new->mask;
> +
> + if (fanotify_is_error_event(old->mask))
> + FANOTIFY_EE(old)->err_count++;
> +
> return 1;
> }
> }
> @@ -577,7 +594,8 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
> static struct fanotify_event *fanotify_alloc_error_event(
> struct fsnotify_group *group,
> __kernel_fsid_t *fsid,
> - const void *data, int data_type)
> + const void *data, int data_type,
> + unsigned int *hash)
> {
> struct fs_error_report *report =
> fsnotify_data_error_report(data, data_type);
> @@ -591,6 +609,10 @@ static struct fanotify_event *fanotify_alloc_error_event(
> return NULL;
>
> fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> + fee->err_count = 1;
> + fee->fsid = *fsid;
> +
> + *hash ^= fanotify_hash_fsid(fsid);
>
> return &fee->fae;
> }
> @@ -664,7 +686,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
> event = fanotify_alloc_perm_event(path, gfp);
> } else if (fanotify_is_error_event(mask)) {
> event = fanotify_alloc_error_event(group, fsid, data,
> - data_type);
> + data_type, &hash);
> } else if (name_event && (file_name || child)) {
> event = fanotify_alloc_name_event(id, fsid, file_name, child,
> &hash, gfp);
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index ebef952481fa..2b032b79d5b0 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -199,6 +199,9 @@ FANOTIFY_NE(struct fanotify_event *event)
>
> struct fanotify_error_event {
> struct fanotify_event fae;
> + u32 err_count; /* Suppressed errors count */
> +
> + __kernel_fsid_t fsid; /* FSID this error refers to. */
> };
>
> static inline struct fanotify_error_event *
> @@ -332,7 +335,6 @@ static inline struct path *fanotify_event_path(struct fanotify_event *event)
> static inline bool fanotify_is_hashed_event(u32 mask)
> {
> return !(fanotify_is_perm_event(mask) ||
> - fanotify_is_error_event(mask) ||
> fsnotify_is_overflow_event(mask));
> }
>
> --
> 2.33.0
>
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