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authorMasami Hiramatsu <mhiramat@kernel.org>2018-01-12 20:56:03 +0300
committerAlexei Starovoitov <ast@kernel.org>2018-01-13 04:33:38 +0300
commit4b1a29a7f5425d32640b34b8a755f34e02f64d0f (patch)
tree1925d4ef5c272c7aedea297359a35eeed505362b /Documentation/fault-injection
parent663faf9f7beeaca4ad0176bb96c776eed9dad0c5 (diff)
downloadlinux-4b1a29a7f5425d32640b34b8a755f34e02f64d0f.tar.xz
error-injection: Support fault injection framework
Support in-kernel fault-injection framework via debugfs. This allows you to inject a conditional error to specified function using debugfs interfaces. Here is the result of test script described in Documentation/fault-injection/fault-injection.txt =========== # ./test_fail_function.sh 1+0 records in 1+0 records out 1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0227404 s, 46.1 MB/s btrfs-progs v4.4 See http://btrfs.wiki.kernel.org for more information. Label: (null) UUID: bfa96010-12e9-4360-aed0-42eec7af5798 Node size: 16384 Sector size: 4096 Filesystem size: 1001.00MiB Block group profiles: Data: single 8.00MiB Metadata: DUP 58.00MiB System: DUP 12.00MiB SSD detected: no Incompat features: extref, skinny-metadata Number of devices: 1 Devices: ID SIZE PATH 1 1001.00MiB /dev/loop2 mount: mount /dev/loop2 on /opt/tmpmnt failed: Cannot allocate memory SUCCESS! =========== Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation/fault-injection')
-rw-r--r--Documentation/fault-injection/fault-injection.txt68
1 files changed, 68 insertions, 0 deletions
diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
index 918972babcd8..f4a32463ca48 100644
--- a/Documentation/fault-injection/fault-injection.txt
+++ b/Documentation/fault-injection/fault-injection.txt
@@ -30,6 +30,12 @@ o fail_mmc_request
injects MMC data errors on devices permitted by setting
debugfs entries under /sys/kernel/debug/mmc0/fail_mmc_request
+o fail_function
+
+ injects error return on specific functions, which are marked by
+ ALLOW_ERROR_INJECTION() macro, by setting debugfs entries
+ under /sys/kernel/debug/fail_function. No boot option supported.
+
Configure fault-injection capabilities behavior
-----------------------------------------------
@@ -123,6 +129,29 @@ configuration of fault-injection capabilities.
default is 'N', setting it to 'Y' will disable failure injections
when dealing with private (address space) futexes.
+- /sys/kernel/debug/fail_function/inject:
+
+ Format: { 'function-name' | '!function-name' | '' }
+ specifies the target function of error injection by name.
+ If the function name leads '!' prefix, given function is
+ removed from injection list. If nothing specified ('')
+ injection list is cleared.
+
+- /sys/kernel/debug/fail_function/injectable:
+
+ (read only) shows error injectable functions and what type of
+ error values can be specified. The error type will be one of
+ below;
+ - NULL: retval must be 0.
+ - ERRNO: retval must be -1 to -MAX_ERRNO (-4096).
+ - ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096).
+
+- /sys/kernel/debug/fail_function/<functiuon-name>/retval:
+
+ specifies the "error" return value to inject to the given
+ function for given function. This will be created when
+ user specifies new injection entry.
+
o Boot option
In order to inject faults while debugfs is not available (early boot time),
@@ -268,6 +297,45 @@ trap "echo 0 > /sys/kernel/debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT
echo "Injecting errors into the module $module... (interrupt to stop)"
sleep 1000000
+------------------------------------------------------------------------------
+
+o Inject open_ctree error while btrfs mount
+
+#!/bin/bash
+
+rm -f testfile.img
+dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1
+DEVICE=$(losetup --show -f testfile.img)
+mkfs.btrfs -f $DEVICE
+mkdir -p tmpmnt
+
+FAILTYPE=fail_function
+FAILFUNC=open_ctree
+echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject
+echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval
+echo N > /sys/kernel/debug/$FAILTYPE/task-filter
+echo 100 > /sys/kernel/debug/$FAILTYPE/probability
+echo 0 > /sys/kernel/debug/$FAILTYPE/interval
+echo -1 > /sys/kernel/debug/$FAILTYPE/times
+echo 0 > /sys/kernel/debug/$FAILTYPE/space
+echo 1 > /sys/kernel/debug/$FAILTYPE/verbose
+
+mount -t btrfs $DEVICE tmpmnt
+if [ $? -ne 0 ]
+then
+ echo "SUCCESS!"
+else
+ echo "FAILED!"
+ umount tmpmnt
+fi
+
+echo > /sys/kernel/debug/$FAILTYPE/inject
+
+rmdir tmpmnt
+losetup -d $DEVICE
+rm testfile.img
+
+
Tool to run command with failslab or fail_page_alloc
----------------------------------------------------
In order to make it easier to accomplish the tasks mentioned above, we can use