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authorNick Piggin <npiggin@suse.de>2009-01-06 17:40:25 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 18:59:09 -0500
commit4f5a99d64c17470a784a6c68064207d82e3e74a5 (patch)
tree2a3e0f0c3990bb8dbda2cdaa506a64180e5cbff2 /include
parente8ea1759138d4279869f52bfb7dca8f02f8ccfe5 (diff)
fs: remove WB_SYNC_HOLD
Remove WB_SYNC_HOLD. The primary motiviation is the design of my anti-starvation code for fsync. It requires taking an inode lock over the sync operation, so we could run into lock ordering problems with multiple inodes. It is possible to take a single global lock to solve the ordering problem, but then that would prevent a future nice implementation of "sync multiple inodes" based on lock order via inode address. Seems like a backward step to remove this, but actually it is busted anyway: we can't use the inode lists for data integrity wait: an inode can be taken off the dirty lists but still be under writeback. In order to satisfy data integrity semantics, we should wait for it to finish writeback, but if we only search the dirty lists, we'll miss it. It would be possible to have a "writeback" list, for sys_sync, I suppose. But why complicate things by prematurely optimise? For unmounting, we could avoid the "livelock avoidance" code, which would be easier, but again premature IMO. Fixing the existing data integrity problem will come next. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/writeback.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index bb28c975c1d7..7300ecdc480c 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -30,7 +30,6 @@ static inline int task_is_pdflush(struct task_struct *task)
30enum writeback_sync_modes { 30enum writeback_sync_modes {
31 WB_SYNC_NONE, /* Don't wait on anything */ 31 WB_SYNC_NONE, /* Don't wait on anything */
32 WB_SYNC_ALL, /* Wait on every mapping */ 32 WB_SYNC_ALL, /* Wait on every mapping */
33 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */
34}; 33};
35 34
36/* 35/*