cp: Expect EINTR while copying
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Authored by des on Sat, Feb 7, 5:34 PM.

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Reviewers

cracauer
asomers
kevans

Commits

rGf1a86b35dedb: cp: Expect EINTR while copying
rGa9ac7da4c0c3: cp: Expect EINTR while copying
rG77385e9fac1c: cp: Expect EINTR while copying
rG7aa30669d6e0: cp: Expect EINTR while copying

Summary

Both copy_file_range() and copy_fallback() can be interrupted before
they have read anything at all, in which case they return -1 and set
errno to EINTR. If that happens, we should retry, not fail.

MFC after: 1 week
PR: 293028

Diff Detail

Repository

rG FreeBSD src repository

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Unit

Tests Skipped

Build Status

Buildable 70560
Build 67443: arc lint + arc unit

Event Timeline

des created this revision.Sat, Feb 7, 5:34 PM

Herald added a subscriber: imp. · View Herald TranscriptSat, Feb 7, 5:34 PM

des requested review of this revision.Sat, Feb 7, 5:34 PM

Harbormaster completed remote builds in B70503: Diff 171421.Sat, Feb 7, 5:34 PM

hang on, that won't actually work, brb

This is probably correct. However, I'd like to see two other things:

A reproduction case
An audit of the rest of the base system for other utilities that make the same mistake, like install(1).

In D55167#1261329, @asomers wrote:

This is probably correct. However, I'd like to see two other things:

A reproduction case

An audit of the rest of the base system for other utilities that make the same mistake, like install(1).

The reproducing case is timing dependent. I came up with the discrepancy when a user on the forums interrupted a cp operation with a du and cp bailed out.

I will troll the base system for similar cases.

In D55167#1261330, @cracauer wrote:

The reproducing case is timing dependent. I came up with the discrepancy when a user on the forums interrupted a cp operation with a du and cp bailed out.

Do you at least know what fuse file system he was using, and what options it was mounted with?

fix loop termination

Harbormaster completed remote builds in B70504: Diff 171422.Sat, Feb 7, 5:46 PM

In D55167#1261331, @asomers wrote:

In D55167#1261330, @cracauer wrote:

The reproducing case is timing dependent. I came up with the discrepancy when a user on the forums interrupted a cp operation with a du and cp bailed out.

Do you at least know what fuse file system he was using, and what options it was mounted with?

NTFS. I just asked the user for flags.

In D55167#1261343, @cracauer wrote:

In D55167#1261331, @asomers wrote:

In D55167#1261330, @cracauer wrote:

The reproducing case is timing dependent. I came up with the discrepancy when a user on the forums interrupted a cp operation with a du and cp bailed out.

Do you at least know what fuse file system he was using, and what options it was mounted with?

NTFS. I just asked the user for flags.

NTFS uses libfuse-2. That version doesn't even support FUSE_COPY_FILE_RANGE. So my guess is that vn_copy_file_range did one read and then one write. The write went through fuse_vnop_write, but then it blocked, because the FUSE daemon was processing other commands. So no FUSE_WRITE operation ever got sent to userspace. Then something sent a signal to the process. So the fusefs module abandoned the write operation, returning EINTR, and vn_copy_file_range faithfully returned it to userspace.

simplify

Harbormaster completed remote builds in B70560: Diff 171593.Mon, Feb 9, 8:09 PM

kevans accepted this revision.Wed, Feb 11, 3:16 PM

This revision is now accepted and ready to land.Wed, Feb 11, 3:16 PM

Closed by commit rG7aa30669d6e0: cp: Expect EINTR while copying (authored by des). · Explain WhyWed, Feb 11, 4:25 PM

This revision was automatically updated to reflect the committed changes.

des added a commit: rG7aa30669d6e0: cp: Expect EINTR while copying.

des added a commit: rG77385e9fac1c: cp: Expect EINTR while copying.Sun, Feb 15, 8:58 AM

des added a commit: rGa9ac7da4c0c3: cp: Expect EINTR while copying.

des added a commit: rGf1a86b35dedb: cp: Expect EINTR while copying.