ext4: Rewrite ext4_page_mkwrite() to use generic helpers

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Rewrite ext4_page_mkwrite() to use __block_page_mkwrite() helper. This
removes the need of using i_alloc_sem to avoid races with truncate which
seems to be the wrong locking order according to lock ordering documented in
mm/rmap.c. Also calling ext4_da_write_begin() as used by the old code seems to
be problematic because we can decide to flush delay-allocated blocks which
will acquire s_umount semaphore - again creating unpleasant lock dependency
if not directly a deadlock.

Also add a check for frozen filesystem so that we don't busyloop in page fault
when the filesystem is frozen.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Jan Kara 2011-06-24 14:29:41 -04:00 • committed by Al Viro

parent 5826869158

commit 9ea7df534e

1 changed files with 55 additions and 51 deletions

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fs/ext4/inode.c

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