[PATCH] statfs.2: Update + Note for pipe() fds

[PATCH] statfs.2: Update + Note for pipe() fds

[Cyril Hrubis]

* Update MAGIC constants, most of them are taken from
  /usr/include/linux/magic.h, some were found by grepping Linux source.

* Add note about fstatfs(2) broken on fd from pipe(2) between
  2.6.38 and 3.2

Signed-off-by: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
---
 man2/statfs.2 | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/man2/statfs.2 b/man2/statfs.2
index 8888307..53cff11 100644
--- a/man2/statfs.2
+++ b/man2/statfs.2
@@ -72,20 +72,30 @@ Filesystem types:
 
    ADFS_SUPER_MAGIC      0xadf5
    AFFS_SUPER_MAGIC      0xADFF
+   BDEVFS_MAGIC          0x62646576
    BEFS_SUPER_MAGIC      0x42465331
    BFS_MAGIC             0x1BADFACE
+   BINFMTFS_MAGIC        0x42494e4d
+   BTRFS_SUPER_MAGIC     0x9123683E
+   CGROUP_SUPER_MAGIC    0x27e0eb
    CIFS_MAGIC_NUMBER     0xFF534D42
    CODA_SUPER_MAGIC      0x73757245
    COH_SUPER_MAGIC       0x012FF7B7
    CRAMFS_MAGIC          0x28cd3d45
+   DEBUGFS_MAGIC         0x64626720
    DEVFS_SUPER_MAGIC     0x1373
+   DEVPTS_SUPER_MAGIC    0x1cd1
+   EFIVARFS_MAGIC        0xde5e81e4
    EFS_SUPER_MAGIC       0x00414A53
    EXT_SUPER_MAGIC       0x137D
    EXT2_OLD_SUPER_MAGIC  0xEF51
    EXT2_SUPER_MAGIC      0xEF53
    EXT3_SUPER_MAGIC      0xEF53
    EXT4_SUPER_MAGIC      0xEF53
+   FUSE_SUPER_MAGIC      0x65735546
+   FUTEXFS_SUPER_MAGIC   0xBAD1DEA
    HFS_SUPER_MAGIC       0x4244
+   HOSTFS_SUPER_MAGIC    0x00c0ffee
    HPFS_SUPER_MAGIC      0xF995E849
    HUGETLBFS_MAGIC       0x958458f6
    ISOFS_SUPER_MAGIC     0x9660
@@ -95,29 +105,47 @@ Filesystem types:
    MINIX_SUPER_MAGIC2    0x138F /* 30 char minix */
    MINIX2_SUPER_MAGIC    0x2468 /* minix V2 */
    MINIX2_SUPER_MAGIC2   0x2478 /* minix V2, 30 char names */
+   MINIX3_SUPER_MAGIC    0x4d5a /* minix V3 fs, 60 char names */
+   MQUEUE_MAGIC          0x19800202
    MSDOS_SUPER_MAGIC     0x4d44
    NCP_SUPER_MAGIC       0x564c
    NFS_SUPER_MAGIC       0x6969
+   NILFS_SUPER_MAGIC     0x3434
    NTFS_SB_MAGIC         0x5346544e
    OPENPROM_SUPER_MAGIC  0x9fa1
+   PIPEFS_MAGIC          0x50495045
    PROC_SUPER_MAGIC      0x9fa0
+   PSTOREFS_MAGIC        0x6165676C
    QNX4_SUPER_MAGIC      0x002f
+   QNX6_SUPER_MAGIC      0x68191122
+   RAMFS_MAGIC           0x858458f6
    REISERFS_SUPER_MAGIC  0x52654973
    ROMFS_MAGIC           0x7275
+   SELINUX_MAGIC         0xf97cff8c
+   SMACK_MAGIC           0x43415d53
    SMB_SUPER_MAGIC       0x517B
+   SOCKFS_MAGIC          0x534F434B
+   SQUASHFS_MAGIC        0x73717368
+   SYSFS_MAGIC           0x62656572
    SYSV2_SUPER_MAGIC     0x012FF7B6
    SYSV4_SUPER_MAGIC     0x012FF7B5
    TMPFS_MAGIC           0x01021994
    UDF_SUPER_MAGIC       0x15013346
    UFS_MAGIC             0x00011954
    USBDEVICE_SUPER_MAGIC 0x9fa2
+   V9FS_MAGIC            0x01021997
    VXFS_SUPER_MAGIC      0xa501FCF5
+   XENFS_SUPER_MAGIC     0xabba1974
    XENIX_SUPER_MAGIC     0x012FF7B4
    XFS_SUPER_MAGIC       0x58465342
    _XIAFS_SUPER_MAGIC    0x012FD16D
 .fi
 .in
 .PP
+Most of these MAGIC constants are defined in
+.I /usr/include/linux/magic.h
+some are hardcoded in kernel sources.
+.PP
 Nobody knows what
 .I f_fsid
 is supposed to contain (but see below).
@@ -221,6 +249,13 @@ Some systems only have \fI<sys/vfs.h>\fP, other systems also have
 So it seems
 including the former is the best choice.
 
+Between Linux 2.6.38 and Linux 3.2
+.\" broken in commit ff0c7d15f9787b7e8c601533c015295cc68329f8
+.\" fixed in commit d70ef97baf048412c395bb5d65791d8fe133a52b
+.BR fstatfs ()
+returned ENOSYS for file descriptor created by
+.BR pipe (2) .
+
 LSB has deprecated the library calls
 .BR statfs ()
 and
-- 
1.8.5.5


-- 
Cyril Hrubis
chrubis-AlSwsSmVLrQ@public.gmane.org
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Re: [PATCH] statfs.2: Update + Note for pipe() fds

[Michael Kerrisk (man-pages)]

Hi Cyril,

Thanks for this. I applied. However, for the future, I really would prefer 
unrelated changes such as the below to be submitted as separate patches.
(I manually split your patch.)

On 06/10/2014 06:04 PM, Cyril Hrubis wrote:
> * Update MAGIC constants, most of them are taken from
>   /usr/include/linux/magic.h, some were found by grepping Linux source.
> 
> * Add note about fstatfs(2) broken on fd from pipe(2) between
>   2.6.38 and 3.2

I moved that patch piece to a (new) BUGS section.

Looking at the following:

$ git describe --contains ff0c7d15f9787b7e8c601533c01529
v2.6.38-rc1~60^2~30
$ git describe --contains d70ef97baf048412c395bb5d65791d
v3.2-rc1~108^2~56

The breakage was from 2.6.38 to 3.1, right? (3.2 fixed things.)
I reworded a little.

And I just want to check. Was it really ff0c7d15f9787b7e8c601533c01529
that caused the breakage? At a quick glance, that patch looks
unrelated, but perhaps something very subtle is going on...

Cheers,

Michael

> Signed-off-by: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
> ---
>  man2/statfs.2 | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/man2/statfs.2 b/man2/statfs.2
> index 8888307..53cff11 100644
> --- a/man2/statfs.2
> +++ b/man2/statfs.2
> @@ -72,20 +72,30 @@ Filesystem types:
>  
>     ADFS_SUPER_MAGIC      0xadf5
>     AFFS_SUPER_MAGIC      0xADFF
> +   BDEVFS_MAGIC          0x62646576
>     BEFS_SUPER_MAGIC      0x42465331
>     BFS_MAGIC             0x1BADFACE
> +   BINFMTFS_MAGIC        0x42494e4d
> +   BTRFS_SUPER_MAGIC     0x9123683E
> +   CGROUP_SUPER_MAGIC    0x27e0eb
>     CIFS_MAGIC_NUMBER     0xFF534D42
>     CODA_SUPER_MAGIC      0x73757245
>     COH_SUPER_MAGIC       0x012FF7B7
>     CRAMFS_MAGIC          0x28cd3d45
> +   DEBUGFS_MAGIC         0x64626720
>     DEVFS_SUPER_MAGIC     0x1373
> +   DEVPTS_SUPER_MAGIC    0x1cd1
> +   EFIVARFS_MAGIC        0xde5e81e4
>     EFS_SUPER_MAGIC       0x00414A53
>     EXT_SUPER_MAGIC       0x137D
>     EXT2_OLD_SUPER_MAGIC  0xEF51
>     EXT2_SUPER_MAGIC      0xEF53
>     EXT3_SUPER_MAGIC      0xEF53
>     EXT4_SUPER_MAGIC      0xEF53
> +   FUSE_SUPER_MAGIC      0x65735546
> +   FUTEXFS_SUPER_MAGIC   0xBAD1DEA
>     HFS_SUPER_MAGIC       0x4244
> +   HOSTFS_SUPER_MAGIC    0x00c0ffee
>     HPFS_SUPER_MAGIC      0xF995E849
>     HUGETLBFS_MAGIC       0x958458f6
>     ISOFS_SUPER_MAGIC     0x9660
> @@ -95,29 +105,47 @@ Filesystem types:
>     MINIX_SUPER_MAGIC2    0x138F /* 30 char minix */
>     MINIX2_SUPER_MAGIC    0x2468 /* minix V2 */
>     MINIX2_SUPER_MAGIC2   0x2478 /* minix V2, 30 char names */
> +   MINIX3_SUPER_MAGIC    0x4d5a /* minix V3 fs, 60 char names */
> +   MQUEUE_MAGIC          0x19800202
>     MSDOS_SUPER_MAGIC     0x4d44
>     NCP_SUPER_MAGIC       0x564c
>     NFS_SUPER_MAGIC       0x6969
> +   NILFS_SUPER_MAGIC     0x3434
>     NTFS_SB_MAGIC         0x5346544e
>     OPENPROM_SUPER_MAGIC  0x9fa1
> +   PIPEFS_MAGIC          0x50495045
>     PROC_SUPER_MAGIC      0x9fa0
> +   PSTOREFS_MAGIC        0x6165676C
>     QNX4_SUPER_MAGIC      0x002f
> +   QNX6_SUPER_MAGIC      0x68191122
> +   RAMFS_MAGIC           0x858458f6
>     REISERFS_SUPER_MAGIC  0x52654973
>     ROMFS_MAGIC           0x7275
> +   SELINUX_MAGIC         0xf97cff8c
> +   SMACK_MAGIC           0x43415d53
>     SMB_SUPER_MAGIC       0x517B
> +   SOCKFS_MAGIC          0x534F434B
> +   SQUASHFS_MAGIC        0x73717368
> +   SYSFS_MAGIC           0x62656572
>     SYSV2_SUPER_MAGIC     0x012FF7B6
>     SYSV4_SUPER_MAGIC     0x012FF7B5
>     TMPFS_MAGIC           0x01021994
>     UDF_SUPER_MAGIC       0x15013346
>     UFS_MAGIC             0x00011954
>     USBDEVICE_SUPER_MAGIC 0x9fa2
> +   V9FS_MAGIC            0x01021997
>     VXFS_SUPER_MAGIC      0xa501FCF5
> +   XENFS_SUPER_MAGIC     0xabba1974
>     XENIX_SUPER_MAGIC     0x012FF7B4
>     XFS_SUPER_MAGIC       0x58465342
>     _XIAFS_SUPER_MAGIC    0x012FD16D
>  .fi
>  .in
>  .PP
> +Most of these MAGIC constants are defined in
> +.I /usr/include/linux/magic.h
> +some are hardcoded in kernel sources.
> +.PP
>  Nobody knows what
>  .I f_fsid
>  is supposed to contain (but see below).
> @@ -221,6 +249,13 @@ Some systems only have \fI<sys/vfs.h>\fP, other systems also have
>  So it seems
>  including the former is the best choice.
>  
> +Between Linux 2.6.38 and Linux 3.2
> +.\" broken in commit ff0c7d15f9787b7e8c601533c015295cc68329f8
> +.\" fixed in commit d70ef97baf048412c395bb5d65791d8fe133a52b
> +.BR fstatfs ()
> +returned ENOSYS for file descriptor created by
> +.BR pipe (2) .
> +
>  LSB has deprecated the library calls
>  .BR statfs ()
>  and
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: [PATCH] statfs.2: Update + Note for pipe() fds

[chrubis-AlSwsSmVLrQ]

Hi!
> > * Update MAGIC constants, most of them are taken from
> >   /usr/include/linux/magic.h, some were found by grepping Linux source.
> > 
> > * Add note about fstatfs(2) broken on fd from pipe(2) between
> >   2.6.38 and 3.2
> 
> I moved that patch piece to a (new) BUGS section.
> 
> Looking at the following:
> 
> $ git describe --contains ff0c7d15f9787b7e8c601533c01529
> v2.6.38-rc1~60^2~30
> $ git describe --contains d70ef97baf048412c395bb5d65791d
> v3.2-rc1~108^2~56
> 
> The breakage was from 2.6.38 to 3.1, right? (3.2 fixed things.)
> I reworded a little.

Ah, right. Sorry for the off by one mistake.

> And I just want to check. Was it really ff0c7d15f9787b7e8c601533c01529
> that caused the breakage? At a quick glance, that patch looks
> unrelated, but perhaps something very subtle is going on...

Yep, it took me a while to notice. If you pass NULL as super_operations
to mount_pseudo() function, which was the case before the patch, default
structure super_operations (with contains only simple_statfs) is used
(have a look at mount_pseudo() in fs/libfs.c). This patch added
pipefs_ops without the statfs callback and passed it instead of the
NULL.

-- 
Cyril Hrubis
chrubis-AlSwsSmVLrQ@public.gmane.org
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Re: [PATCH] statfs.2: Update + Note for pipe() fds

[Michael Kerrisk (man-pages)]

>> And I just want to check. Was it really ff0c7d15f9787b7e8c601533c01529
>> that caused the breakage? At a quick glance, that patch looks
>> unrelated, but perhaps something very subtle is going on...
>
> Yep, it took me a while to notice. If you pass NULL as super_operations
> to mount_pseudo() function, which was the case before the patch, default
> structure super_operations (with contains only simple_statfs) is used
> (have a look at mount_pseudo() in fs/libfs.c). This patch added
> pipefs_ops without the statfs callback and passed it instead of the
> NULL.

Ahh -- okay. Thanks for the explanation.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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