ocfs2: Avoid livelock in ocfs2_readpage()

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When someone writes to an inode, readers accessing the same inode via
ocfs2_readpage() just busyloop trying to get ip_alloc_sem because
do_generic_file_read() looks up the page again and retries ->readpage()
when previous attempt failed with AOP_TRUNCATED_PAGE. When there are enough
readers, they can occupy all CPUs and in non-preempt kernel the system is
deadlocked because writer holding ip_alloc_sem is never run to release the
semaphore. Fix the problem by making reader block on ip_alloc_sem to break
the busy loop.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <jlbec@evilplan.org>

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Jan Kara 2011-06-23 22:51:47 +02:00 • committed by Joel Becker

parent a11f7e63c5

commit c7e25e6e0b

1 changed files with 8 additions and 0 deletions

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fs/ocfs2/aops.c

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