This is a note to let you know that I've just added the patch titled
btrfs: refresh dir last index during a rewinddir(3) call
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-refresh-dir-last-index-during-a-rewinddir-3-call.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e60aa5da14d01fed8411202dbe4adf6c44bd2a57 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana@xxxxxxxx>
Date: Sat, 9 Sep 2023 13:08:32 +0100
Subject: btrfs: refresh dir last index during a rewinddir(3) call
From: Filipe Manana <fdmanana@xxxxxxxx>
commit e60aa5da14d01fed8411202dbe4adf6c44bd2a57 upstream.
When opening a directory we find what's the index of its last entry and
then store it in the directory's file handle private data (struct
btrfs_file_private::last_index), so that in the case new directory entries
are added to a directory after an opendir(3) call we don't end up in an
infinite loop (see commit 9b378f6ad48c ("btrfs: fix infinite directory
reads")) when calling readdir(3).
However once rewinddir(3) is called, POSIX states [1] that any new
directory entries added after the previous opendir(3) call, must be
returned by subsequent calls to readdir(3):
"The rewinddir() function shall reset the position of the directory
stream to which dirp refers to the beginning of the directory.
It shall also cause the directory stream to refer to the current
state of the corresponding directory, as a call to opendir() would
have done."
We currently don't refresh the last_index field of the struct
btrfs_file_private associated to the directory, so after a rewinddir(3)
we are not returning any new entries added after the opendir(3) call.
Fix this by finding the current last index of the directory when llseek
is called against the directory.
This can be reproduced by the following C program provided by Ian Johnson:
#include <dirent.h>
#include <stdio.h>
int main(void) {
DIR *dir = opendir("test");
FILE *file;
file = fopen("test/1", "w");
fwrite("1", 1, 1, file);
fclose(file);
file = fopen("test/2", "w");
fwrite("2", 1, 1, file);
fclose(file);
rewinddir(dir);
struct dirent *entry;
while ((entry = readdir(dir))) {
printf("%s\n", entry->d_name);
}
closedir(dir);
return 0;
}
Reported-by: Ian Johnson <ian@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-btrfs/YR1P0S.NGASEG570GJ8@xxxxxxxxxxxxxx/
Fixes: 9b378f6ad48c ("btrfs: fix infinite directory reads")
CC: stable@xxxxxxxxxxxxxxx # 6.5+
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/inode.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5979,6 +5979,19 @@ static int btrfs_opendir(struct inode *i
return 0;
}
+static loff_t btrfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct btrfs_file_private *private = file->private_data;
+ int ret;
+
+ ret = btrfs_get_dir_last_index(BTRFS_I(file_inode(file)),
+ &private->last_index);
+ if (ret)
+ return ret;
+
+ return generic_file_llseek(file, offset, whence);
+}
+
struct dir_entry {
u64 ino;
u64 offset;
@@ -11059,7 +11072,7 @@ static const struct inode_operations btr
};
static const struct file_operations btrfs_dir_file_operations = {
- .llseek = generic_file_llseek,
+ .llseek = btrfs_dir_llseek,
.read = generic_read_dir,
.iterate_shared = btrfs_real_readdir,
.open = btrfs_opendir,
Patches currently in stable-queue which might be from fdmanana@xxxxxxxx are
queue-6.5/btrfs-refresh-dir-last-index-during-a-rewinddir-3-call.patch
queue-6.5/btrfs-assert-delayed-node-locked-when-removing-delay.patch
queue-6.5/btrfs-set-last-dir-index-to-the-current-last-index-when-opening-dir.patch
queue-6.5/btrfs-remove-bug-after-failure-to-insert-delayed-dir.patch
queue-6.5/btrfs-improve-error-message-after-failure-to-add-del.patch
queue-6.5/btrfs-fix-race-between-reading-a-directory-and-adding-entries-to-it.patch
