Filesystem: try umount first during stop-action, and avoid potential "Argument list too long" for force_unmount=safe #1977
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
48ed6e6 (Filesystem: improve stop-action and allow setting term/kill signals and signal_delay for large filesystems, 2023-07-04) changed the logic from "try umount; if that fails, find and kill users; repeat" to "try to find and kill users; then try umount; repeat" But even just walking /proc may take "a long time" on busy systems, and may still turn up with "no users found". It will take even longer for "force_umount=safe" (observed 8 to 10 seconds just for "get_pids() with "safe" to return nothing) than for "force_umount=yes" (still ~ 2 to 3 seconds), but it will take "a long time" in any case. (BTW, that may be longer than the hardcoded default of 6 seconds for "fast_stop", which is also the default on many systems now) If the dependencies are properly configured, there should be no users left, and the umount should just work. Revert back to "try umount first", and only then try to find "rogue" users.
The "safe" way to get process ids that may be using a particular filesystem
currently uses shell globs ("find /proc/[0-9]*").
With a million processes (and/or a less capable shell),
that may result in "Argument list too long".
Replace with find /proc -path "/proc/[0-9]*" instead.
While at it, also fix the non-posix -or to be -o,
and add explicit grouping parentheses \( \) and explicit -print.
Add a comment to not include "interesting" characters in mount point names.
|
Impressive work! |
oalbrigt
changed the title
|
Thanks. |
|
if scanning /proc twice should become a problem, we could either use bash and its more advance redirections, or use fifos procs=$(
exec 2>/dev/null
D=$(mktemp -d) # (preferably somwhere on a tmpfs, so set TMPDIR or add -p or an explicit template)
mkfifo "$D/maps";
(
< "$D/maps" xargs -r grep -l " $dir/" | cut -d/ -f3 | uniq &
exec 3> "$D/maps";
rm -rf "$D";
find /proc -path '/proc/[0-9]*' \
\( -name maps -fprint "/dev/fd/3" \
-o -type l \( -lname "$dir/*" -o -lname "$dir" \) -print \
\) | cut -d/ -f 3 | uniq
) | sort -u
)😜 |
|
Feel free to make a patch when you got the time. We should keep it non-bash specific, as the agent can also be used on *BSD. |
#1978 (hope that is sufficiently *BSD compatible ...) |
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.
See individual commit messages.