[Bug 111891] New: access to file does not change access time to folders above up to /(root)

[Bug 111891] New: access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

            Bug ID: 111891
           Summary: access to file does not change access time to folders
                    above up to /(root)
           Product: File System
           Version: 2.5
    Kernel Version: 4.1.15
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
          Assignee: fs_ext4@kernel-bugs.osdl.org
          Reporter: armin_mohring@web.de
        Regression: No

Ext4 with relatime mount option.

Access to file e.g.: /home/armin/documents/abc (file)
does lead into the following:

The access time of the /home directory is not changed, but should be.

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

Andreas Dilger <adilger.kernelbugzilla@dilger.ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adilger.kernelbugzilla@dilg
                   |                            |er.ca

--- Comment #1 from Andreas Dilger <adilger.kernelbugzilla@dilger.ca> ---
I'm not sure where you got the idea that the access time of all parent
directories should be changed, but that isn't how POSIX works. Only the access
time of the file will be modified, otherwise there would be a huge amount of
overhead (e.g. maybe dozens of disk writes) for every file access.

Also, most filesystems have no way of determining the parent directories for a
given file, and there may be multiple parent directories for a single file
(hard links), and it wouldn't make sense to update all of those directories, so
this is also impractical to implement for most filesystems.

People have enough problems with atime without making it even more expensive,
and relatime is already reducing the number of cases where atime is updated
significantly.

Seems I cannot close this bug (Ted, can you give me permission for this?), but
it should be closed as "not a bug".

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

Armin Mohring <armin_mohring@web.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WILL_NOT_FIX

--- Comment #2 from Armin Mohring <armin_mohring@web.de> ---
I thought it would be a good idea to change this behaviour.

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

--- Comment #3 from Armin Mohring <armin_mohring@web.de> ---
I think, only symbolic links should be used.

The parent directory is given by the directory tree itself. Stored in a tree.

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED
                 CC|                            |tytso@mit.edu
         Resolution|WILL_NOT_FIX                |INVALID

--- Comment #4 from Theodore Tso <tytso@mit.edu> ---
Andreas, I don't have access to change the access controls.  We need to ask the
bugzilla.kernel.org admins to add you to the appropriate ACL.

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

--- Comment #5 from Armin Mohring <armin_mohring@web.de> ---
The additional write amount is not so big as expected.

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[Bug 111891] access to file does not change access time to folders above up to /(root)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=111891

--- Comment #6 from Armin Mohring <armin_mohring@web.de> ---
Just backtrace the directory tree.
Modern firesystems use trees for storing the directory information.

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