* [PATCH 4/4] ext4: fix end of region partial cluster handling
@ 2014-11-21 14:59 Eric Whitney
2014-11-23 6:05 ` Theodore Ts'o
0 siblings, 1 reply; 3+ messages in thread
From: Eric Whitney @ 2014-11-21 14:59 UTC (permalink / raw)
To: linux-ext4; +Cc: tytso
ext4_ext_remove_space() can incorrectly free a partial_cluster if
EAGAIN is encountered while truncating or punching. Extent removal
should be retried in this case.
It also fails to free a partial cluster when the punched region begins
at the start of a file on that unaligned cluster and where the entire
file has not been punched. Remove the requirement that all blocks in
the file must have been freed in order to free the partial cluster.
Signed-off-by: Eric Whitney <enwlinux@gmail.com>
---
fs/ext4/extents.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 841adf0..9eae2f4 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3009,16 +3009,18 @@ again:
trace_ext4_ext_remove_space_done(inode, start, end, depth,
partial_cluster, path->p_hdr->eh_entries);
- /* If we still have something in the partial cluster and we have removed
+ /*
+ * If we still have something in the partial cluster and we have removed
* even the first extent, then we should free the blocks in the partial
- * cluster as well. */
- if (partial_cluster > 0 && path->p_hdr->eh_entries == 0) {
- int flags = get_default_free_blocks_flags(inode);
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH 4/4] ext4: fix end of region partial cluster handling
2014-11-21 14:59 [PATCH 4/4] ext4: fix end of region partial cluster handling Eric Whitney
@ 2014-11-23 6:05 ` Theodore Ts'o
2014-11-23 17:05 ` Eric Whitney
0 siblings, 1 reply; 3+ messages in thread
From: Theodore Ts'o @ 2014-11-23 6:05 UTC (permalink / raw)
To: Eric Whitney; +Cc: linux-ext4
On Fri, Nov 21, 2014 at 09:59:04AM -0500, Eric Whitney wrote:
> ext4_ext_remove_space() can incorrectly free a partial_cluster if
> EAGAIN is encountered while truncating or punching. Extent removal
> should be retried in this case.
I don't see anything in the patch below which retries the extent
removal; am I missing something?
Thanks,
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 4/4] ext4: fix end of region partial cluster handling
2014-11-23 6:05 ` Theodore Ts'o
@ 2014-11-23 17:05 ` Eric Whitney
0 siblings, 0 replies; 3+ messages in thread
From: Eric Whitney @ 2014-11-23 17:05 UTC (permalink / raw)
To: Theodore Ts'o; +Cc: Eric Whitney, linux-ext4
The retry occurs at the end of ext4_ext_remove_space where the code loops
back to the top of the function if err == -EAGAIN, leading to another call
to ext4_ext_rm_leaf. Nothing new needs to be added - we simply want to
avoid using invalid state to decide whether to free a partial cluster (on
occurrence of -EAGAIN), and the existing retry loop will eventually get us
valid state.
(I actually saw this in testing, but it takes a lot of runs to get there.)
Sorry if I edited down my comment a little too far - I'd be happy to beef
that up if desired.
Thanks,
Eric
* Theodore Ts'o <tytso@mit.edu>:
> On Fri, Nov 21, 2014 at 09:59:04AM -0500, Eric Whitney wrote:
> > ext4_ext_remove_space() can incorrectly free a partial_cluster if
> > EAGAIN is encountered while truncating or punching. Extent removal
> > should be retried in this case.
>
> I don't see anything in the patch below which retries the extent
> removal; am I missing something?
>
> Thanks,
>
> - Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
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