0eb03c7e8e
Bug fixes:
- The eventfs directories need to have unique inode numbers. Make sure that
they do not get the default file inode number.
- Update the inode uid and gid fields on remount.
When a remount happens where a uid and/or gid is specified, all the tracefs
files and directories should get the specified uid and/or gid. But this
can be sporadic when some uids were assigned already. There's already
a list of inodes that are allocated. Just update their uid and gid fields
at the time of remount.
- Update the eventfs_inodes on remount from the top level "events" descriptor.
There was a bug where not all the eventfs files or directories where
getting updated on remount. One fix was to clear the SAVED_UID/GID
flags from the inode list during the iteration of the inodes during
the remount. But because the eventfs inodes can be freed when the last
referenced is released, not all the eventfs_inodes were being updated.
This lead to the ownership selftest to fail if it was run a second
time (the first time would leave eventfs_inodes with no corresponding
tracefs_inode).
Instead, for eventfs_inodes, only process the "events" eventfs_inode
from the list iteration, as it is guaranteed to have a tracefs_inode
(it's never freed while the "events" directory exists). As it has
a list of its children, and the children have a list of their children,
just iterate all the eventfs_inodes from the "events" descriptor and
it is guaranteed to get all of them.
- Clear the EVENT_INODE flag from the tracefs_drop_inode() callback.
Currently the EVENTFS_INODE FLAG is cleared in the tracefs_d_iput()
callback. But this is the wrong location. The iput() callback is
called when the last reference to the dentry inode is hit. There could
be a case where two dentry's have the same inode, and the flag will
be cleared prematurely. The flag needs to be cleared when the last
reference of the inode is dropped and that happens in the inode's
drop_inode() callback handler.
Clean ups:
- Consolidate the creation of a tracefs_inode for an eventfs_inode
A tracefs_inode is created for both files and directories of the
eventfs system. It is open coded. Instead, consolidate it into a
single eventfs_get_inode() function call.
- Remove the eventfs getattr and permission callbacks.
The permissions for the eventfs files and directories are updated
when the inodes are created, on remount, and when the user sets
them (via setattr). The inodes hold the current permissions so
there is no need to have custom getattr or permissions callbacks
as they will more likely cause them to be incorrect. The inode's
permissions are updated when they should be updated. Remove the
getattr and permissions inode callbacks.
- Do not update eventfs_inode attributes on creation of inodes.
The eventfs_inodes attribute field is used to store the permissions
of the directories and files for when their corresponding inodes
are freed and are created again. But when the creation of the inodes
happen, the eventfs_inode attributes are recalculated. The
recalculation should only happen when the permissions change for
a given file or directory. Currently, the attribute changes are
just being set to their current files so this is not a bug, but
it's unnecessary and error prone. Stop doing that.
- The events directory inode is created once when the events directory
is created and deleted when it is deleted. It is now updated on
remount and when the user changes the permissions. There's no need
to use the eventfs_inode of the events directory to store the
events directory permissions. But using it to store the default
permissions for the files within the directory that have not been
updated by the user can simplify the code.
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Merge tag 'trace-tracefs-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracefs/eventfs updates from Steven Rostedt:
"Bug fixes:
- The eventfs directories need to have unique inode numbers. Make
sure that they do not get the default file inode number.
- Update the inode uid and gid fields on remount.
When a remount happens where a uid and/or gid is specified, all the
tracefs files and directories should get the specified uid and/or
gid. But this can be sporadic when some uids were assigned already.
There's already a list of inodes that are allocated. Just update
their uid and gid fields at the time of remount.
- Update the eventfs_inodes on remount from the top level "events"
descriptor.
There was a bug where not all the eventfs files or directories
where getting updated on remount. One fix was to clear the
SAVED_UID/GID flags from the inode list during the iteration of the
inodes during the remount. But because the eventfs inodes can be
freed when the last referenced is released, not all the
eventfs_inodes were being updated. This lead to the ownership
selftest to fail if it was run a second time (the first time would
leave eventfs_inodes with no corresponding tracefs_inode).
Instead, for eventfs_inodes, only process the "events"
eventfs_inode from the list iteration, as it is guaranteed to have
a tracefs_inode (it's never freed while the "events" directory
exists). As it has a list of its children, and the children have a
list of their children, just iterate all the eventfs_inodes from
the "events" descriptor and it is guaranteed to get all of them.
- Clear the EVENT_INODE flag from the tracefs_drop_inode() callback.
Currently the EVENTFS_INODE FLAG is cleared in the tracefs_d_iput()
callback. But this is the wrong location. The iput() callback is
called when the last reference to the dentry inode is hit. There
could be a case where two dentry's have the same inode, and the
flag will be cleared prematurely. The flag needs to be cleared when
the last reference of the inode is dropped and that happens in the
inode's drop_inode() callback handler.
Cleanups:
- Consolidate the creation of a tracefs_inode for an eventfs_inode
A tracefs_inode is created for both files and directories of the
eventfs system. It is open coded. Instead, consolidate it into a
single eventfs_get_inode() function call.
- Remove the eventfs getattr and permission callbacks.
The permissions for the eventfs files and directories are updated
when the inodes are created, on remount, and when the user sets
them (via setattr). The inodes hold the current permissions so
there is no need to have custom getattr or permissions callbacks as
they will more likely cause them to be incorrect. The inode's
permissions are updated when they should be updated. Remove the
getattr and permissions inode callbacks.
- Do not update eventfs_inode attributes on creation of inodes.
The eventfs_inodes attribute field is used to store the permissions
of the directories and files for when their corresponding inodes
are freed and are created again. But when the creation of the
inodes happen, the eventfs_inode attributes are recalculated. The
recalculation should only happen when the permissions change for a
given file or directory. Currently, the attribute changes are just
being set to their current files so this is not a bug, but it's
unnecessary and error prone. Stop doing that.
- The events directory inode is created once when the events
directory is created and deleted when it is deleted. It is now
updated on remount and when the user changes the permissions.
There's no need to use the eventfs_inode of the events directory to
store the events directory permissions. But using it to store the
default permissions for the files within the directory that have
not been updated by the user can simplify the code"
* tag 'trace-tracefs-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
eventfs: Do not use attributes for events directory
eventfs: Cleanup permissions in creation of inodes
eventfs: Remove getattr and permission callbacks
eventfs: Consolidate the eventfs_inode update in eventfs_get_inode()
tracefs: Clear EVENT_INODE flag in tracefs_drop_inode()
eventfs: Update all the eventfs_inodes from the events descriptor
tracefs: Update inode permissions on remount
eventfs: Keep the directories from having the same inode number as files
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.