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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2020/04/29 23:10:24 UTC
[GitHub] [incubator-nuttx] Oxore opened a new issue #912: tmpfs: tmpfs_statfs recursively removes files
Oxore opened a new issue #912:
URL: https://github.com/apache/incubator-nuttx/issues/912
# Steps to reproduce
## Prerequisites
Linux environment. `arm-none-eabi-gcc` toolchain, gcc version 9.3.0. QEMU with ARM emulation.
**NuttX commit:** 5b839061f960cadb3fda19a51679484b95f8d6e3
**Apps commit:** dcc620e6b8418f81615f7875db56ed443ac642d6
## Preparation
Let's assume we have cloned NuttX repo into `/nuttx` and apps repo into `/apps`. Current working directory: `/nuttx`. Prepare config:
./tools/configure.sh -l -a ../apps lm3s6965-ek:nsh
Adjust configuration:
CONFIG_TIVA_ETHERNET=n
CONFIG_NET=n
CONFIG_FS_TMPFS=y
CONFIG_FS_PROCFS=y
Build:
CROSSDEV=arm-none-eabi- make
Run:
qemu-system-arm -M lm3s6965evb -kernel ./nuttx
Go to `serial0` (Ctrl+Alt+3) and get the console.
## Actual steps to reproduce
At `nsh` prompt type:
mkdir /tmp/dir
echo >/tmp/file
echo >/tmp/dir/file2
ls /tmp
ls /tmp/dir
You can see created files and directory. Now run the following:
df
or:
cat /proc/fs/usage
then run:
ls /tmp
ls /tmp/dir
There is no `/tmp/dir/file2` anymore, but `/tmp/file` still exists, though. So files in `/tmp` always exist, but any directory in `/tmp` becomes recursively cleaned up.
I expect, that when I run `df`, all my files in `/tmp` and deeper do not get changed or deleted, but they disappear.
# Possible fix or just pointing to a buggy line of code
When file `/proc/fs/tmpfs` is being read, it's `read` op calls `tmpfs_statfs`, that has subsequent call to `tmpfs_foreach`, which contains unconditional recursive call to itself with `tmpfs_free_callout` value being passed to the argument `callout`. This is why all files **in all directories of** `/tmp` disappear, but files and directories in `/tmp` (the root of `tmpfs`) stay on.
Here is an "one line" fix:
```diff
diff --git a/fs/tmpfs/fs_tmpfs.c b/fs/tmpfs/fs_tmpfs.c
index 43fb0fc081..915ccb6aec 100644
--- a/fs/tmpfs/fs_tmpfs.c
+++ b/fs/tmpfs/fs_tmpfs.c
@@ -1322,7 +1322,7 @@ static int tmpfs_foreach(FAR struct tmpfs_directory_s *tdo,
* action will be to delete the directory.
*/
- ret = tmpfs_foreach(next, tmpfs_free_callout, NULL);
+ ret = tmpfs_foreach(next, callout, arg);
if (ret < 0)
{
return -ECANCELED;
```
So...
**Does it fix the bug?** Yes, it looks like it fixes it. If we create more files we get values increased in `df` output for `/tmp` and all files in `/tmp` and in it's directories persist.
**Does it introduce more bugs?** I don't know.
How can I test it? I hope that original author has better understanding of what is going on here and how to properly fix the bug.
I can try to open a pull request and carefully adjust all the code around, if somebody explain how I test my changes or at least point the places where to put attention to.
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[GitHub] [incubator-nuttx] xiaoxiang781216 commented on issue #912: tmpfs: tmpfs_statfs recursively removes files
Posted by GitBox <gi...@apache.org>.
xiaoxiang781216 commented on issue #912:
URL: https://github.com/apache/incubator-nuttx/issues/912#issuecomment-621570571
@Oxore thanks for the detailed bug report and analysis. Your change looks correctly, could you open a PR?
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