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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2009-02-14 10:42:58 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-02-14 10:42:58 -0500
commit2acf2c261b823d9d9ed954f348b97620297a36b5 (patch)
tree01bcc80ee26a9cc25df9b9a215081943f3fcbd6c
parentd794bf8e0936dce45104565cd48c571061f4c1e3 (diff)
downloadlinux-2acf2c261b823d9d9ed954f348b97620297a36b5.tar.bz2
ext4: Implement range_cyclic in ext4_da_writepages instead of write_cache_pages
With delayed allocation we lock the page in write_cache_pages() and try to build an in memory extent of contiguous blocks. This is needed so that we can get large contiguous blocks request. If range_cyclic mode is enabled, write_cache_pages() will loop back to the 0 index if no I/O has been done yet, and try to start writing from the beginning of the range. That causes an attempt to take the page lock of lower index page while holding the page lock of higher index page, which can cause a dead lock with another writeback thread. The solution is to implement the range_cyclic behavior in ext4_da_writepages() instead. http://bugzilla.kernel.org/show_bug.cgi?id=12579 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/inode.c21
1 files changed, 19 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 658c4a7f2578..cbd2ca99d113 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2439,6 +2439,7 @@ static int ext4_da_writepages(struct address_space *mapping,
int no_nrwrite_index_update;
int pages_written = 0;
long pages_skipped;
+ int range_cyclic, cycled = 1, io_done = 0;
int needed_blocks, ret = 0, nr_to_writebump = 0;
struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
@@ -2490,9 +2491,15 @@ static int ext4_da_writepages(struct address_space *mapping,
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
- if (wbc->range_cyclic)
+ range_cyclic = wbc->range_cyclic;
+ if (wbc->range_cyclic) {
index = mapping->writeback_index;
- else
+ if (index)
+ cycled = 0;
+ wbc->range_start = index << PAGE_CACHE_SHIFT;
+ wbc->range_end = LLONG_MAX;
+ wbc->range_cyclic = 0;
+ } else
index = wbc->range_start >> PAGE_CACHE_SHIFT;
mpd.wbc = wbc;
@@ -2506,6 +2513,7 @@ static int ext4_da_writepages(struct address_space *mapping,
wbc->no_nrwrite_index_update = 1;
pages_skipped = wbc->pages_skipped;
+retry:
while (!ret && wbc->nr_to_write > 0) {
/*
@@ -2548,6 +2556,7 @@ static int ext4_da_writepages(struct address_space *mapping,
pages_written += mpd.pages_written;
wbc->pages_skipped = pages_skipped;
ret = 0;
+ io_done = 1;
} else if (wbc->nr_to_write)
/*
* There is no more writeout needed
@@ -2556,6 +2565,13 @@ static int ext4_da_writepages(struct address_space *mapping,
*/
break;
}
+ if (!io_done && !cycled) {
+ cycled = 1;
+ index = 0;
+ wbc->range_start = index << PAGE_CACHE_SHIFT;
+ wbc->range_end = mapping->writeback_index - 1;
+ goto retry;
+ }
if (pages_skipped != wbc->pages_skipped)
printk(KERN_EMERG "This should not happen leaving %s "
"with nr_to_write = %ld ret = %d\n",
@@ -2563,6 +2579,7 @@ static int ext4_da_writepages(struct address_space *mapping,
/* Update index */
index += pages_written;
+ wbc->range_cyclic = range_cyclic;
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
/*
* set the writeback_index so that range_cyclic