Re: [RFC][PATCH] inotify 0.13.1
From: Robert Love (rml_at_novell.com)
Date: 10/08/04
- Previous message: Hanna Linder: "[PATCH 2.6][10/12] prep_pci.c replace pci_find_device with pci_get_device"
- In reply to: John McCutchan: "[RFC][PATCH] inotify 0.13.1"
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To: John McCutchan <ttb@tentacle.dhs.org> Date: Thu, 07 Oct 2004 19:37:36 -0400
OK.
I am working on redoing the inotify locking wrt inodes.
Most of the time that we grab inode->i_lock, we don't need it. We do
need it when allocating or freeing inode->inotify_data. We also need it
when first obtaining the inotify_data reference count (see below).
So we need an inotify_data reference count to track its lifetime. We
already have ->watcher_count, which functions pretty well as this ref
count, but we need to formalize it, make it atomic_t, and always grab it
under ->i_lock. Freeing the structure is then a consequence of the ref
count dropping to zero via atomic_dec_and_test().
Then we can add inotify_data->lock to protect the contents of
inotify_data from concurrent access and not use i_lock.
Anyone dereferencing inotify_data (or setting/freeing it for the first
time) needs to hold a ref count. This is an existing bug.
We can hopefully end up only taking inode->i_lock when grabbing this ref
count, and no other time. We won't have to nest it with dev->lock any
more.
That is the plan, anyhow. Patch later tonight or tomorrow, with luck.
Robert Love
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- Previous message: Hanna Linder: "[PATCH 2.6][10/12] prep_pci.c replace pci_find_device with pci_get_device"
- In reply to: John McCutchan: "[RFC][PATCH] inotify 0.13.1"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
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