[PATCH v2] fanotify.7,fanotify_mark.2: update documentation of fanotify w.r.t fsid

[PATCH v2] fanotify.7,fanotify_mark.2: update documentation of fanotify w.r.t fsid

[Amir Goldstein]

Clarify the conditions for getting the -EXDEV and -ENODEV errors.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

Changes since v1:
- Fix review comments [1]

[1] https://lore.kernel.org/linux-fsdevel/20241101130732.xzpottv5ru63w4wd@devuan/

 man/man2/fanotify_mark.2 | 27 +++++++++++++++++++++------
 man/man7/fanotify.7      | 11 +++++++++++
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/man/man2/fanotify_mark.2 b/man/man2/fanotify_mark.2
index fc9b83459..47cafb21c 100644
--- a/man/man2/fanotify_mark.2
+++ b/man/man2/fanotify_mark.2
@@ -659,17 +659,16 @@ The filesystem object indicated by
 .I dirfd
 and
 .I pathname
-is not associated with a filesystem that supports
+is associated with a filesystem that reports zero
 .I fsid
 (e.g.,
 .BR fuse (4)).
-.BR tmpfs (5)
-did not support
-.I fsid
-prior to Linux 5.13.
-.\" commit 59cda49ecf6c9a32fae4942420701b6e087204f6
 This error can be returned only with an fanotify group that identifies
 filesystem objects by file handles.
+Since Linux 6.8,
+.\" commit 30ad1938326bf9303ca38090339d948975a626f5
+this error can be returned
+when trying to add a mount or filesystem mark.
 .TP
 .B ENOENT
 The filesystem object indicated by
@@ -768,6 +767,22 @@ which uses a different
 than its root superblock.
 This error can be returned only with an fanotify group that identifies
 filesystem objects by file handles.
+Since Linux 6.8,
+.\" commit 30ad1938326bf9303ca38090339d948975a626f5
+this error will be returned
+when trying to add a mount or filesystem mark on a subvolume,
+when trying to add inode marks in different subvolumes,
+or when trying to add inode marks in a
+.BR btrfs (5)
+subvolume and in another filesystem.
+Since Linux 6.8,
+.\" commit 30ad1938326bf9303ca38090339d948975a626f5
+this error will also be returned
+when trying to add marks in different filesystems,
+where one of the filesystems reports zero
+.I fsid
+(e.g.,
+.BR fuse (4)).
 .SH STANDARDS
 Linux.
 .SH HISTORY
diff --git a/man/man7/fanotify.7 b/man/man7/fanotify.7
index 449af949c..b270f3c99 100644
--- a/man/man7/fanotify.7
+++ b/man/man7/fanotify.7
@@ -575,6 +575,17 @@ and contains the same value as
 .I f_fsid
 when calling
 .BR statfs (2).
+Note that some filesystems (e.g.,
+.BR fuse (4))
+report zero
+.IR fsid .
+In these cases,
+it is not possible to use
+.I fsid
+to associate the event with a specific filesystem instance,
+so monitoring different filesystem instances that report zero
+.I fsid
+with the same fanotify group is not supported.
 .TP
 .I handle
 This field contains a variable-length structure of type
-- 
2.34.1

Re: [PATCH v2] fanotify.7,fanotify_mark.2: update documentation of fanotify w.r.t fsid

[Alejandro Colomar]

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Hi Amir,

On Tue, Nov 05, 2024 at 03:49:39PM GMT, Amir Goldstein wrote:
> Clarify the conditions for getting the -EXDEV and -ENODEV errors.
> 
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Patch applied.  Thanks!
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=f6ebb46dfba40902656321f16bfb38daf4d99377>

I've also applied Jan's Review tag, since the changes are minimal.
BTW, I would appreciate range-diffs, as recommended in
<./CONTRIBUTING.d/patches>.

Please have a look at these:
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING.d/patches>
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING.d/git>

Have a lovely night!
Alex

> ---
> 
> Changes since v1:
> - Fix review comments [1]
> 
> [1] https://lore.kernel.org/linux-fsdevel/20241101130732.xzpottv5ru63w4wd@devuan/
> 
>  man/man2/fanotify_mark.2 | 27 +++++++++++++++++++++------
>  man/man7/fanotify.7      | 11 +++++++++++
>  2 files changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/man/man2/fanotify_mark.2 b/man/man2/fanotify_mark.2
> index fc9b83459..47cafb21c 100644
> --- a/man/man2/fanotify_mark.2
> +++ b/man/man2/fanotify_mark.2
> @@ -659,17 +659,16 @@ The filesystem object indicated by
>  .I dirfd
>  and
>  .I pathname
> -is not associated with a filesystem that supports
> +is associated with a filesystem that reports zero
>  .I fsid
>  (e.g.,
>  .BR fuse (4)).
> -.BR tmpfs (5)
> -did not support
> -.I fsid
> -prior to Linux 5.13.
> -.\" commit 59cda49ecf6c9a32fae4942420701b6e087204f6
>  This error can be returned only with an fanotify group that identifies
>  filesystem objects by file handles.
> +Since Linux 6.8,
> +.\" commit 30ad1938326bf9303ca38090339d948975a626f5
> +this error can be returned
> +when trying to add a mount or filesystem mark.
>  .TP
>  .B ENOENT
>  The filesystem object indicated by
> @@ -768,6 +767,22 @@ which uses a different
>  than its root superblock.
>  This error can be returned only with an fanotify group that identifies
>  filesystem objects by file handles.
> +Since Linux 6.8,
> +.\" commit 30ad1938326bf9303ca38090339d948975a626f5
> +this error will be returned
> +when trying to add a mount or filesystem mark on a subvolume,
> +when trying to add inode marks in different subvolumes,
> +or when trying to add inode marks in a
> +.BR btrfs (5)
> +subvolume and in another filesystem.
> +Since Linux 6.8,
> +.\" commit 30ad1938326bf9303ca38090339d948975a626f5
> +this error will also be returned
> +when trying to add marks in different filesystems,
> +where one of the filesystems reports zero
> +.I fsid
> +(e.g.,
> +.BR fuse (4)).
>  .SH STANDARDS
>  Linux.
>  .SH HISTORY
> diff --git a/man/man7/fanotify.7 b/man/man7/fanotify.7
> index 449af949c..b270f3c99 100644
> --- a/man/man7/fanotify.7
> +++ b/man/man7/fanotify.7
> @@ -575,6 +575,17 @@ and contains the same value as
>  .I f_fsid
>  when calling
>  .BR statfs (2).
> +Note that some filesystems (e.g.,
> +.BR fuse (4))
> +report zero
> +.IR fsid .
> +In these cases,
> +it is not possible to use
> +.I fsid
> +to associate the event with a specific filesystem instance,
> +so monitoring different filesystem instances that report zero
> +.I fsid
> +with the same fanotify group is not supported.
>  .TP
>  .I handle
>  This field contains a variable-length structure of type
> -- 
> 2.34.1
> 

-- 
<https://www.alejandro-colomar.es/>

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