On 1/28/25 12:12 PM, Greg KH wrote:
On Tue, Jan 28, 2025 at 03:03:22PM +0000, ciprietti@xxxxxxxxxx wrote:From: yangerkun <yangerkun@xxxxxxxxxx> [ Upstream commit 64a7ce76fb901bf9f9c36cf5d681328fc0fd4b5a ] After we switch tmpfs dir operations from simple_dir_operations to simple_offset_dir_operations, every rename happened will fill new dentry to dest dir's maple tree(&SHMEM_I(inode)->dir_offsets->mt) with a free key starting with octx->newx_offset, and then set newx_offset equals to free key + 1. This will lead to infinite readdir combine with rename happened at the same time, which fail generic/736 in xfstests(detail show as below). 1. create 5000 files(1 2 3...) under one dir 2. call readdir(man 3 readdir) once, and get one entry 3. rename(entry, "TEMPFILE"), then rename("TEMPFILE", entry) 4. loop 2~3, until readdir return nothing or we loop too many times(tmpfs break test with the second condition) We choose the same logic what commit 9b378f6ad48cf ("btrfs: fix infinite directory reads") to fix it, record the last_index when we open dir, and do not emit the entry which index >= last_index. The file->private_data now used in offset dir can use directly to do this, and we also update the last_index when we llseek the dir file. Fixes: a2e459555c5f ("shmem: stable directory offsets") Signed-off-by: yangerkun <yangerkun@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240731043835.1828697-1-yangerkun@xxxxxxxxxx Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx> [brauner: only update last_index after seek when offset is zero like Jan suggested] Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Andrea Ciprietti <ciprietti@xxxxxxxxxx> --- fs/libfs.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-)No hint as to what kernel tree(s) this is for?
Just to be absolutely clear: NAK - there are some problems already reported with this patch upstream. We have a patch series pending that addresses this issue in v6.6: https://lore.kernel.org/linux-fsdevel/20250124191946.22308-1-cel@xxxxxxxxxx/ -- Chuck Lever
