On Tue, Jan 28, 2025 at 03:03:22PM +0000, ciprietti@google.com wrote:
From: yangerkun yangerkun@huawei.com
[ 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).
- create 5000 files(1 2 3...) under one dir
- call readdir(man 3 readdir) once, and get one entry
- rename(entry, "TEMPFILE"), then rename("TEMPFILE", entry)
- 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@huawei.com Link: https://lore.kernel.org/r/20240731043835.1828697-1-yangerkun@huawei.com Reviewed-by: Chuck Lever chuck.lever@oracle.com [brauner: only update last_index after seek when offset is zero like Jan suggested] Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Andrea Ciprietti ciprietti@google.com
You forgot to mention what you changed.
fs/libfs.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c index dc0f7519045f..916c39e758b1 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -371,6 +371,15 @@ void simple_offset_destroy(struct offset_ctx *octx) xa_destroy(&octx->xa); } +static int offset_dir_open(struct inode *inode, struct file *file) +{
- struct offset_ctx *ctx = inode->i_op->get_offset_ctx(inode);
- unsigned long next_offset = (unsigned long)ctx->next_offset;
- file->private_data = (void *)next_offset;
Why do you need 2 casts here when the original did not?
thanks,
greg k-h