os/filestore: fix punch hole usage in _zero #8050
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
If we punch a hole that extends past EOF, ObjectStore semantics are that the file size is also extended. Do that. Note that this bug was hidden before because we weren't passing KEEP_SIZE to fallocate until 7bd95b5 and the fallocate was *always* failing with EOPNOTSUPP (making us fall back to writing actual zeros). Signed-off-by: Sage Weil <sage@redhat.com>
Make punch hole usage optional. Default to off, since it's relatively untested. Signed-off-by: Sage Weil <sage@redhat.com>
| } else { | ||
| // ensure we extent file size, if needed | ||
| if (offset + len > st.st_size) { | ||
| ret = ::ftruncate(**fd, offset + len); |
There was a problem hiding this comment.
I'm a little nervous about this, what if we want to zero 10->5 and size is 12. from my glancing view, 12-15 will be zeroed, but what about 10-12 section(not zeroed)?
Another thought: it looks like PUNCH_HOLE isn't fullly match _zero semantic, FALLOC_FL_ZERO_RANGE may better
There was a problem hiding this comment.
The fallocate call should zero 10-12. Truncate just ensure we end up with
size=15 at the end.
I think PUNCH_HOLE is a closer fit. Both zero teh region logically, but
ZERO_RANGE preallocates, and I don't think we want that.
There was a problem hiding this comment.
oh, I have a misunderstand on this bug.
|
lgtm |
liewegas
added a commit
that referenced
this pull request
Mar 14, 2016
os/filestore: fix punch hole usage in _zero Reviewed-by: Samuel Just <sjust@redhat.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
If we punch a hole that extends past EOF, ObjectStore semantics are
that the file size is also extended. Do that.
Note that this bug was hidden before because we weren't passing
KEEP_SIZE to fallocate until 7bd95b5
and the fallocate was always failing with EOPNOTSUPP (making us fall
back to writing actual zeros).
Signed-off-by: Sage Weil sage@redhat.com