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Fix reversion introduced in 6.20171214 that caused concurrent transfers to incorrectly fail with "transfer already in progress".

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Avoid creating transfer info file before transfer lock is created and
locked.

The wrong order for one thing caused transfer info to be overwritten
when a transfer was already in progress.

But worse, it caused checkTransfer to see the transfer info,
and so lock the transfer lock in order to verify the transfer was not in
progress. Which in a concurrent situation, prevented the transferrer
from locking the transfer lock, so it failed with "transfer already in
progress".

Note that the transferinfo command does not lock the transfer lock
before creating the transfer info. But, that's only run after
recvkey is running, and recvkey does lock the transfer lock, so that
seems more or less ok. (Other than being a super complicated legacy mess
that the P2P code has mostly obsoleted now.)

This commit was supported by the NSF-funded DataLad project.
This commit is contained in:
Joey Hess 2018-03-14 18:55:27 -04:00
parent da1b1fb991
commit 10d3b7fc62
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GPG key ID: DB12DB0FF05F8F38
6 changed files with 27 additions and 14 deletions
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14
Annex/Transfer.hs
View file

@ -73,9 +73,9 @@ alwaysRunTransfer = runTransfer' True
runTransfer' :: Observable v => Bool -> Transfer -> AssociatedFile -> RetryDecider -> (MeterUpdate -> Annex v) -> Annex v
runTransfer' ignorelock t afile shouldretry transferaction = checkSecureHashes t $ do
info <- liftIO $ startTransferInfo afile
(meter, tfile, metervar) <- mkProgressUpdater t info
(meter, tfile, createtfile, metervar) <- mkProgressUpdater t info
mode <- annexFileMode
(lck, inprogress) <- prep tfile mode info
(lck, inprogress) <- prep tfile createtfile mode
if inprogress && not ignorelock
then do
showNote "transfer already in progress, or unable to take transfer lock"
@ -89,30 +89,28 @@ runTransfer' ignorelock t afile shouldretry transferaction = checkSecureHashes t
return v
where
#ifndef mingw32_HOST_OS
prep tfile mode info = catchPermissionDenied (const prepfailed) $ do
prep tfile createtfile mode = catchPermissionDenied (const prepfailed) $ do
let lck = transferLockFile tfile
createAnnexDirectory $ takeDirectory lck
tryLockExclusive (Just mode) lck >>= \case
Nothing -> return (Nothing, True)
Just lockhandle -> ifM (checkSaneLock lck lockhandle)
( do
void $ tryIO $
writeTransferInfoFile info tfile
createtfile
return (Just lockhandle, False)
, do
liftIO $ dropLock lockhandle
return (Nothing, True)
)
#else
prep tfile _mode info = catchPermissionDenied (const prepfailed) $ do
prep tfile createtfile _mode = catchPermissionDenied (const prepfailed) $ do
let lck = transferLockFile tfile
createAnnexDirectory $ takeDirectory lck
catchMaybeIO (liftIO $ lockExclusive lck) >>= \case
Nothing -> return (Nothing, False)
Just Nothing -> return (Nothing, True)
Just (Just lockhandle) -> do
void $ tryIO $
writeTransferInfoFile info tfile
createtfile
return (Just lockhandle, False)
#endif
prepfailed = return (Nothing, False)