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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2008-07-11 19:27:31 -0400
committerTheodore Ts'o <tytso@mit.edu>2008-07-11 19:27:31 -0400
commit06d6cf6959d22037fcec598f4f954db5db3d7356 (patch)
tree3248c7a27114031ac3d0012080a97932a6190469
parentd2a1763791a634e315ec926b62829c1e88842c86 (diff)
mm: Add range_cont mode for writeback
Filesystems like ext4 needs to start a new transaction in the writepages for block allocation. This happens with delayed allocation and there is limit to how many credits we can request from the journal layer. So we call write_cache_pages multiple times with wbc->nr_to_write set to the maximum possible value limitted by the max journal credits available. Add a new mode to writeback that enables us to handle this behaviour. In the new mode we update the wbc->range_start to point to the new offset to be written. Next call to call to write_cache_pages will start writeout from specified range_start offset. In the new mode we also limit writing to the specified wbc->range_end. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--include/linux/writeback.h1
-rw-r--r--mm/page-writeback.c3
2 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index f462439cc28..0d8573e6b9e 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -63,6 +63,7 @@ struct writeback_control {
unsigned for_writepages:1; /* This is a writepages() call */
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned more_io:1; /* more io to be dispatched */
+ unsigned range_cont:1;
};
/*
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 789b6adbef3..ded57d52806 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -956,6 +956,9 @@ retry:
}
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
mapping->writeback_index = index;
+
+ if (wbc->range_cont)
+ wbc->range_start = index << PAGE_CACHE_SHIFT;
return ret;
}
EXPORT_SYMBOL(write_cache_pages);