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Consider the following case: 1. A glock is held in shared mode. 2. A process requests the glock in exclusive mode (rename). 3. Before the lock is granted, more processes (read / ls) request the glock in shared mode again. 4. gfs2 sends a request to dlm for the lock in exclusive mode because that holder is at the head of the queue. 5. Somehow the dlm request gets canceled, so dlm sends us back a response with state == LM_ST_SHARED and LM_OUT_CANCELED. So at that point, the glock is still held in shared mode. 6. finish_xmote gets called to process the response from dlm. It detects that the glock is not in the requested mode and no demote is in progress, so it moves the canceled holder to the tail of the queue and finds the new holder at the head of the queue. That holder is requesting the glock in shared mode. 7. finish_xmote calls do_xmote to transition the glock into shared mode, but the glock is already in shared mode and so do_xmote complains about that with: GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target); Instead, in finish_xmote, after moving the canceled holder to the tail of the queue, check if any new holders can be granted. Only call do_xmote to repeat the dlm request if the holder at the head of the queue is requesting the glock in a mode that is incompatible with the mode the glock is currently held in. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> |
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| fs | ||
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| init | ||
| io_uring | ||
| ipc | ||
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| lib | ||
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| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .rustfmt.toml | ||
| COPYING | ||
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| README | ||
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 Restructured Text 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.