From ae62bcb5e7e5a1ab6f85518949f3f759c6e9a8e0 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Mon, 23 Oct 2023 17:30:49 +0300 Subject: fs: report f_fsid from s_dev for "simple" filesystems There are many "simple" filesystems (*) that report null f_fsid in statfs(2). Those "simple" filesystems report sb->s_dev as the st_dev field of the stat syscalls for all inodes of the filesystem (**). In order to enable fanotify reporting of events with fsid on those "simple" filesystems, report the sb->s_dev number in f_fsid field of statfs(2). (*) For most of the "simple" filesystem refered to in this commit, the ->statfs() operation is simple_statfs(). Some of those fs assign the simple_statfs() method directly in their ->s_op struct and some assign it indirectly via a call to simple_fill_super() or to pseudo_fs_fill_super() with either custom or "simple" s_op. We also make the same change to efivarfs and hugetlbfs, although they do not use simple_statfs(), because they use the simple_* inode opreations (e.g. simple_lookup()). (**) For most of the "simple" filesystems, the ->getattr() method is not assigned, so stat() is implemented by generic_fillattr(). A few "simple" filesystem use the simple_getattr() method which also calls generic_fillattr() to fill most of the stat struct. The two exceptions are procfs and 9p. procfs implements several different ->getattr() methods, but they all end up calling generic_fillattr() to fill the st_dev field from sb->s_dev. 9p has more complicated ->getattr() methods, but they too, end up calling generic_fillattr() to fill the st_dev field from sb->s_dev. Note that 9p and kernfs also call simple_statfs() from custom ->statfs() methods which already fill the f_fsid field, but v9fs_statfs() calls simple_statfs() only in case f_fsid was not filled and kenrfs_statfs() overwrites f_fsid after calling simple_statfs(). Link: https://lore.kernel.org/r/20230919094820.g5bwharbmy2dq46w@quack3/ Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20231023143049.2944970-1-amir73il@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- fs/efivarfs/super.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/efivarfs/super.c') diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index 996271473609..2933090ad11f 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -30,6 +30,7 @@ static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS; u64 storage_space, remaining_space, max_variable_size; + u64 id = huge_encode_dev(dentry->d_sb->s_dev); efi_status_t status; /* Some UEFI firmware does not implement QueryVariableInfo() */ @@ -53,6 +54,7 @@ static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) buf->f_blocks = storage_space; buf->f_bfree = remaining_space; buf->f_type = dentry->d_sb->s_magic; + buf->f_fsid = u64_to_fsid(id); /* * In f_bavail we declare the free space that the kernel will allow writing -- cgit v1.2.3-58-ga151