Commit graph

21 commits

Author SHA1 Message Date
Leo Luan
ff0280c0cb vfs: Fix missed concurrency control between some item operations and reset
Item reset is invoked by cache cleaner for synchronous recovery
from ENOSPC errors. The reset operation removes the cache file and
closes/reopens the downloaders.  Although most parts of reset and
other item operations are done with the item mutex held, the mutex
is released during fd.WriteAt and downloaders calls. We used preAccess
and postAccess calls to serialize Reset, ReadAt, and Open, but missed
some other item operations. The patch adds preAccess/postAccess
calls in Sync, Truncate, Close, WriteAt, and rename.
2020-10-06 16:35:23 +01:00
Nick Craig-Wood
18ccf0f871 vfs: detect and recover from a file being removed externally from the cache
Before this change if a file was removed from the cache while rclone
is running then rclone would not notice and proceed to re-create it
full of zeros.

This change notices files that we expect to have data in going missing
and if they do logs an ERROR recovers.

It isn't recommended deleting files from the cache manually with
rclone running!

See: https://forum.rclone.org/t/corrupted-data-streaming-after-vfs-meta-files-removed/18997
Fixes #4602
2020-09-18 10:30:02 +01:00
Nick Craig-Wood
6a56ac1032 vfs,local: Log an ERROR if we fail to set the file to be sparse
See: https://forum.rclone.org/t/rclone-1-53-release/18880/73
2020-09-11 15:36:47 +01:00
Nick Craig-Wood
27b9ae4fc3 vfs: fix spurious error "vfs cache: failed to _ensure cache EOF"
Before this change the error message was produced for every file which
was confusing users.

After this change we check for EOF and return from ReadAt at that
point.

See: https://forum.rclone.org/t/rclone-1-53-release/18880/10
2020-09-03 10:25:00 +01:00
Leo Luan
c665201b85 vfs: support synchronous cache space recovery upon ENOSPC
This patch provides the support of synchronous cache space recovery
to allow read threads to recover from ENOSPC errors when cache space
can be recovered from cache items that are not in use or safe to be
reset/emptied .

The patch complements the existing cache cleaning process in two ways.

Firstly, the existing cache cleaning process is time-driven that runs
periodically. The cache space can run out while the cache cleaner
thread is still waiting for its next scheduled run. The io threads
encountering ENOSPC return an internal error to the applications
in this case even when cache space can be recovered to avoid this
error. This patch addresses this problem by having the read threads
kick the cache cleaner thread in this condition to recover cache
space preventing unnecessary ENOSPC errors from being seen by the
applications.

Secondly, this patch enhances the cache cleaner to support cache
item reset. Currently the cache purge process removes cache
items that are not in use. This may not be sufficient when the
total size of the working set exceeds the cache directory's
capacity. Like in the current code, this patch starts the purge
process by removing cache files that are not in use. Cache items
whose access times are older than vfs-cache-max-age are removed first.
After that, other not-in-use items are removed in LRU order until
vfs-cache-max-size is reached. If the vfs-cache-max-size (the quota)
is still not reached at this time, this patch adds a cache reset
step to reset/empty cache files that are still in use but not
dirtied.  This enables application processes to continue without
seeing an error even when the working set depletes the cache space
as long as there is not a large write working set hoarding the
entire cache space.

By design this patch does not add ENOSPC error recovery for write
IOs. Rclone does not empty a write cache item until the file data
is written back to the backend upon close. Allowing more cache
space to be consumed by dirty cache items when the cache space is
already running low would increase the risk of exhausting the cache
space in a way that the vfs mount becomes unreadable.
2020-08-25 21:12:06 +01:00
Nick Craig-Wood
94a0991584 vfs: set the modtime of the cache file immediately
Before this change we set the modtime of the cache file when all
writers had finished.

This has the unfortunate effect that the file is uploaded with the
wrong modtime which means on backends which can't set modtimes except
when uploading files it is wrong.

This change sets the modtime of the cache file immediately in the
cache and in turn sets the modtime in the file info.
2020-08-20 16:24:04 +01:00
Nick Craig-Wood
b2f4f52b64 vfs cache: make logging consistent and remove some debug logging 2020-07-06 17:32:53 +01:00
Nick Craig-Wood
c65ed26a7e vfs: vfscache: Fix renaming of items while they are being uploaded
Previous to the fix, if an item was being uploaded and it was renamed,
the upload would fail with missing checksum errors.

This change cancels any uploads in progress if the file is renamed.
2020-07-06 17:32:53 +01:00
Nick Craig-Wood
63ebe4ca8d vfs: Reduce logging of metadata expiry to debug 2020-07-02 14:52:12 +01:00
Nick Craig-Wood
15402e46c9 vfs: Add recovered items on cache reload to directory listings
Before this change, if we restarted an upload after a restart then the
file would get uploaded but never added to the directory listings.

This change makes sure we add virtual items to the directory cache
when reloading the cache so that they show up properly.
2020-06-30 12:03:39 +01:00
Nick Craig-Wood
530dc77cde vfs: Fix race condition in vfscache 2020-06-30 12:03:39 +01:00
Nick Craig-Wood
ee04732cbb vfs: factor writeback and downloaders into their own packages 2020-06-30 12:03:39 +01:00
Nick Craig-Wood
d273a9d82d vfs: remove items from writeback when dirty, don't just cancel the upload
This stops open items continually trying to be uploaded
2020-06-30 12:03:39 +01:00
Nick Craig-Wood
43018973ac vfs: decouple writeback from Item so it can be tested 2020-06-30 12:01:36 +01:00
Nick Craig-Wood
fa472a340e vfs: fix writeback deadlocks and other bugs
- fix deadlock when cancelling upload
- fix double upload and panic after cancelled upload
- fix cancelation strategy of uploading files
    - don't cancel uploads if we don't modify the file
    - cancel uploads if we do modify the file
- fix deadlock between Item and writeback
- fix confusion about whether writeback item was being uploaded
- fix cornercases in cancelling uploads and removing files
2020-06-30 12:01:36 +01:00
Nick Craig-Wood
279a516c53 vfs: add tests and fix bugs for vfscache.Item
Item
- Remove unused method getName
- Fix Truncate on unopened file
- Fix bug when downloading segments to fill out file on close
- Fix bug when WriteAt extends the file and we don't mark space as used

downloader
- Retry failed waiters every 5 seconds
2020-06-30 12:01:36 +01:00
Nick Craig-Wood
9ac5c6de14 vfs: cache: rework file downloader
- Download to multiple places at once in the stream
- Restart as necessary
- Timeout unused downloaders
- Close reader if too much data skipped
- Only use one file handle as use item for writing
- Implement --vfs-read-chunk-size and --vfs-read-chunk-limit
- fix deadlock between asyncbuffer and vfs cache downloader
- fix display of stream abandoned error which should be ignored
2020-06-30 12:01:36 +01:00
Nick Craig-Wood
58a7faa281 vfs: Make tests run reliably
On file Remove
- cancel any writebacks in progress
- ignore error message deleting non existent file if file was in the
  process of being uploaded

Writeback
- Don't transfer the file if it has disappeared in the meantime
- Take our own copy of the file name to avoid deadlocks
- Fix delayed retry logic
- Wait for upload to finish when cancelling upload

Fix race condition in item saving

Fix race condition in vfscache test

Make sure we delete the file on the error path - this makes cascading
failures much less likely
2020-06-30 12:01:36 +01:00
Nick Craig-Wood
496a87a665 vfs: restart pending uploads on restart of the cache 2020-06-30 12:01:36 +01:00
Nick Craig-Wood
e4e53a2e61 vfs: add --vfs-writeback option to delay writes back to cloud storage
This is enabled by default and can be disabled with --vfs-writeback 0
2020-06-30 12:01:36 +01:00
Nick Craig-Wood
917cb4acb3 vfs: implement partial reads in --vfs-cache-mode full
This allows reads to only read part of the file and it keeps on disk a
cache of what parts of each file have been loaded.

File data itself is kept in sparse files.
2020-06-30 12:01:36 +01:00