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authorAndrea Arcangeli <andrea@suse.de>2005-10-30 15:03:05 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-30 17:37:26 -0800
commit7f04c26d715a2467a49a2384268de8f70f787b51 (patch)
tree8507e9f705f063d996857789261b762b24fad94f /fs/inode.c
parent52303e8b5f8aa234865d40d76ea16b0ff4b27022 (diff)
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[PATCH] fix nr_unused accounting, and avoid recursing in iput with I_WILL_FREE set
list_move(&inode->i_list, &inode_in_use); } else { list_move(&inode->i_list, &inode_unused); + inodes_stat.nr_unused++; } } wake_up_inode(inode); Are you sure the above diff is correct? It was added somewhere between 2.6.5 and 2.6.8. I think it's wrong. The only way I can imagine the i_count to be zero in the above path, is that I_WILL_FREE is set. And if I_WILL_FREE is set, then we must not increase nr_unused. So I believe the above change is buggy and it will definitely overstate the number of unused inodes and it should be backed out. Note that __writeback_single_inode before calling __sync_single_inode, can drop the spinlock and we can have both the dirty and locked bitflags clear here: spin_unlock(&inode_lock); __wait_on_inode(inode); iput(inode); XXXXXXX spin_lock(&inode_lock); } use inode again here a construct like the above makes zero sense from a reference counting standpoint. Either we don't ever use the inode again after the iput, or the inode_lock should be taken _before_ executing the iput (i.e. a __iput would be required). Taking the inode_lock after iput means the iget was useless if we keep using the inode after the iput. So the only chance the 2.6 was safe to call __writeback_single_inode with the i_count == 0, is that I_WILL_FREE is set (I_WILL_FREE will prevent the VM to free the inode in XXXXX). Potentially calling the above iput with I_WILL_FREE was also wrong because it would recurse in iput_final (the second mainline bug). The below (untested) patch fixes the nr_unused accounting, avoids recursing in iput when I_WILL_FREE is set and makes sure (with the BUG_ON) that we don't corrupt memory and that all holders that don't set I_WILL_FREE, keeps a reference on the inode! Signed-off-by: Andrea Arcangeli <andrea@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/inode.c')
-rw-r--r--fs/inode.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 7d3316527767..d8d04bd72b59 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1088,6 +1088,7 @@ static void generic_forget_inode(struct inode *inode)
if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
+ wake_up_inode(inode);
destroy_inode(inode);
}