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From: Amir Goldstein <amir73il@gmail.com>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Jan Kara <jack@suse.com>, "Darrick J. Wong" <djwong@kernel.org>,
	Theodore Tso <tytso@mit.edu>, David Howells <dhowells@redhat.com>,
	Khazhismel Kumykov <khazhy@google.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Ext4 <linux-ext4@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Matthew Bobrowski <repnop@google.com>,
	kernel@collabora.com
Subject: Re: [PATCH v7 23/28] fanotify: Report fid info for file related file system errors
Date: Fri, 15 Oct 2021 10:56:38 +0300	[thread overview]
Message-ID: <CAOQ4uxgR9jGSyGoHvDEPpSpMVHGssnkXJJ5a8HRKD6nxMyMLmA@mail.gmail.com> (raw)
In-Reply-To: <20211014213646.1139469-24-krisman@collabora.com>

On Fri, Oct 15, 2021 at 12:39 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Plumb the pieces to add a FID report to error records.  Since all error
> event memory must be pre-allocated, we pre-allocate the maximum file
> handle size possible, such that it should always fit.
>
> For errors that don't expose a file handle report it with an invalid
> FID.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>
> ---
> Changes since v6:
>   - pass fsid from handle_events
> Changes since v5:
>   - Use preallocated MAX_HANDLE_SZ FH buffer
>   - Report superblock errors with a zerolength INVALID FID (jan, amir)
> ---
>  fs/notify/fanotify/fanotify.c | 15 +++++++++++++++
>  fs/notify/fanotify/fanotify.h |  8 ++++++++
>  2 files changed, 23 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 7032083df62a..8a60c96f5fb2 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -611,7 +611,9 @@ static struct fanotify_event *fanotify_alloc_error_event(
>  {
>         struct fs_error_report *report =
>                         fsnotify_data_error_report(data, data_type);
> +       struct inode *inode = report->inode;
>         struct fanotify_error_event *fee;
> +       int fh_len;
>
>         if (WARN_ON(!report))
>                 return NULL;
> @@ -622,6 +624,19 @@ static struct fanotify_event *fanotify_alloc_error_event(
>
>         fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
>         fee->err_count = 1;
> +       fee->fsid = *fsid;
> +
> +       fh_len = fanotify_encode_fh_len(inode);
> +       if (WARN_ON(fh_len > MAX_HANDLE_SZ)) {

WARN_ON_ONCE please and I rather that this sanity check is moved inside
fanotify_encode_fh_len() where it will return 0 for encoding failure.

> +               /*
> +                * Fallback to reporting the error against the super
> +                * block.  It should never happen.
> +                */
> +               inode = NULL;
> +               fh_len = fanotify_encode_fh_len(NULL);
> +       }
> +
> +       fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
>
>         *hash ^= fanotify_hash_fsid(fsid);
>
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index 2b032b79d5b0..b58400926f92 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -202,6 +202,10 @@ struct fanotify_error_event {
>         u32 err_count; /* Suppressed errors count */
>
>         __kernel_fsid_t fsid; /* FSID this error refers to. */
> +       /* object_fh must be followed by the inline handle buffer. */
> +       struct fanotify_fh object_fh;
> +       /* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */
> +       unsigned char _inline_fh_buf[MAX_HANDLE_SZ];
>  };

This struct duplicates most of struct fanotify_fid_event.
How about:

#define FANOTIFY_ERROR_FH_LEN \
             (MAX_HANDLE_SZ - FANOTIFY_INLINE_FH_LEN)

struct fanotify_error_event {
         u32 err_count; /* Suppressed errors count */
         struct fanotify_event ffe;
         /* Reserve space in ffe.object_fh.buf[] - access with
fanotify_fh_buf() */
         unsigned char _fh_buf[FANOTIFY_ERROR_FH_LEN];
}

Or leaving out the struct padding and passing
FANOTIFY_ERROR_EVENT_SIZE as mempool object size?

#define FANOTIFY_ERROR_EVENT_SIZE \
            (sizeof(struct fanotify_error_event) + FANOTIFY_ERROR_FH_LEN)

You do not have to make this change - it is a proposal that can have
supporters and objectors, so let's wait to see what you and other reviewers
have to say.

Thanks,
Amir.

  reply	other threads:[~2021-10-15  7:56 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14 21:36 [PATCH v7 00/28] file system-wide error monitoring Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 01/28] fsnotify: pass data_type to fsnotify_name() Gabriel Krisman Bertazi
2021-10-15  9:18   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 02/28] fsnotify: pass dentry instead of inode data Gabriel Krisman Bertazi
2021-10-15 13:39   ` Jan Kara
2021-10-18  9:11   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 03/28] fsnotify: clarify contract for create event hooks Gabriel Krisman Bertazi
2021-10-15  9:21   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 04/28] fsnotify: Don't insert unmergeable events in hashtable Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 05/28] fanotify: Fold event size calculation to its own function Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 06/28] fanotify: Split fsid check from other fid mode checks Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 07/28] inotify: Don't force FS_IN_IGNORED Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 08/28] fsnotify: Add helper to detect overflow_event Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 09/28] fsnotify: Add wrapper around fsnotify_add_event Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 10/28] fsnotify: Retrieve super block from the data field Gabriel Krisman Bertazi
2021-10-15  5:39   ` Amir Goldstein
2021-10-15  9:26   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 11/28] fsnotify: Pass group argument to free_event Gabriel Krisman Bertazi
2021-10-15  5:40   ` Amir Goldstein
2021-10-15  9:26   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 12/28] fanotify: Support null inode event in fanotify_dfid_inode Gabriel Krisman Bertazi
2021-10-15  5:49   ` Amir Goldstein
2021-10-15  9:30   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 13/28] fanotify: Allow file handle encoding for unhashed events Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 14/28] fanotify: Encode empty file handle when no inode is provided Gabriel Krisman Bertazi
2021-10-15  6:02   ` Amir Goldstein
2021-10-15  9:32   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 15/28] fanotify: Require fid_mode for any non-fd event Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 16/28] fsnotify: Support FS_ERROR event type Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 17/28] fanotify: Reserve UAPI bits for FAN_FS_ERROR Gabriel Krisman Bertazi
2021-10-15  9:37   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 18/28] fanotify: Pre-allocate pool of error events Gabriel Krisman Bertazi
2021-10-15  6:19   ` Amir Goldstein
2021-10-15  7:33     ` Amir Goldstein
2021-10-15  9:46   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 19/28] fanotify: Limit number of marks with FAN_FS_ERROR per group Gabriel Krisman Bertazi
2021-10-15  6:15   ` Amir Goldstein
2021-10-15 16:53     ` Gabriel Krisman Bertazi
2021-10-15 17:49       ` Amir Goldstein
2021-10-14 21:36 ` [PATCH v7 20/28] fanotify: Support enqueueing of error events Gabriel Krisman Bertazi
2021-10-15  7:04   ` Amir Goldstein
2021-10-15 16:50     ` Gabriel Krisman Bertazi
2021-10-15 12:34   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 21/28] fanotify: Support merging " Gabriel Krisman Bertazi
2021-10-15  7:09   ` Amir Goldstein
2021-10-15 16:54     ` Gabriel Krisman Bertazi
2021-10-15 17:52       ` Amir Goldstein
2021-10-18 13:55         ` Gabriel Krisman Bertazi
2021-10-15 12:43   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 22/28] fanotify: Report FID entry even for zero-length file_handle Gabriel Krisman Bertazi
2021-10-15  8:10   ` Amir Goldstein
2021-10-15 13:13     ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 23/28] fanotify: Report fid info for file related file system errors Gabriel Krisman Bertazi
2021-10-15  7:56   ` Amir Goldstein [this message]
2021-10-15 13:38     ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 24/28] fanotify: Emit generic error info for error event Gabriel Krisman Bertazi
2021-10-15  8:13   ` Amir Goldstein
2021-10-15 12:47   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 25/28] fanotify: Allow users to request FAN_FS_ERROR events Gabriel Krisman Bertazi
2021-10-15  8:27   ` Amir Goldstein
2021-10-15 12:49   ` Jan Kara
2021-10-14 21:36 ` [PATCH v7 26/28] ext4: Send notifications on error Gabriel Krisman Bertazi
2021-10-14 21:59   ` Theodore Ts'o
2021-10-14 21:36 ` [PATCH v7 27/28] samples: Add fs error monitoring example Gabriel Krisman Bertazi
2021-10-14 21:36 ` [PATCH v7 28/28] docs: Document the FAN_FS_ERROR event Gabriel Krisman Bertazi
2021-10-15  8:38 ` [PATCH v7 00/28] file system-wide error monitoring Amir Goldstein
2021-10-15  9:16 ` Jan Kara

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