The patch titled
r/o bind mounts: elevate writer count for custom 'struct file'
has been removed from the -mm tree. Its filename is
ro-bind-mounts-elevate-writer-count-for-custom-struct-file.patch
This patch was dropped because Viro's comments sounded rather serious
------------------------------------------------------
Subject: r/o bind mounts: elevate writer count for custom 'struct file'
From: Dave Hansen <haveblue@xxxxxxxxxx>
Some filesystems forego the vfs and may_open() and create their own 'struct
file's. Any of these users which set the write flag on the file will cause an
extra mnt_drop_write() on __fput(), thus dropping the reference count too low.
These users tend to have artifical in-kernel vfsmounts which aren't really
exposed to userspace and can't be remounted, but this patch is included for
completeness and so that the warnings don't trip over these cases.
Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
Cc: Serge Hallyn <serue@xxxxxxxxxx>
Cc: Herbert Poetzl <herbert@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/hugetlbfs/inode.c | 2 ++
mm/shmem.c | 2 ++
mm/tiny-shmem.c | 2 ++
net/socket.c | 3 +++
4 files changed, 9 insertions(+)
diff -puN fs/hugetlbfs/inode.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file fs/hugetlbfs/inode.c
--- a/fs/hugetlbfs/inode.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file
+++ a/fs/hugetlbfs/inode.c
@@ -790,6 +790,8 @@ struct file *hugetlb_zero_setup(size_t s
file->f_mapping = inode->i_mapping;
file->f_op = &hugetlbfs_file_operations;
file->f_mode = FMODE_WRITE | FMODE_READ;
+ error = mnt_want_write(hugetlbfs_vfsmount);
+ WARN_ON(error);
return file;
out_inode:
diff -puN mm/shmem.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file mm/shmem.c
--- a/mm/shmem.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file
+++ a/mm/shmem.c
@@ -2326,6 +2326,8 @@ struct file *shmem_file_setup(char *name
file->f_mapping = inode->i_mapping;
file->f_op = &shmem_file_operations;
file->f_mode = FMODE_WRITE | FMODE_READ;
+ error = mnt_want_write(shm_mnt);
+ WARN_ON(error);
return file;
close_file:
diff -puN mm/tiny-shmem.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file mm/tiny-shmem.c
--- a/mm/tiny-shmem.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file
+++ a/mm/tiny-shmem.c
@@ -88,6 +88,8 @@ struct file *shmem_file_setup(char *name
file->f_mapping = inode->i_mapping;
file->f_op = &ramfs_file_operations;
file->f_mode = FMODE_WRITE | FMODE_READ;
+ error = mnt_want_write(shm_mnt);
+ WARN_ON(error);
/* notify everyone as to the change of file size */
error = do_truncate(dentry, size, 0, file);
diff -puN net/socket.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file net/socket.c
--- a/net/socket.c~ro-bind-mounts-elevate-writer-count-for-custom-struct-file
+++ a/net/socket.c
@@ -396,6 +396,7 @@ static int sock_attach_fd(struct socket
{
struct qstr this;
char name[32];
+ int error;
this.len = sprintf(name, "[%lu]", SOCK_INODE(sock)->i_ino);
this.name = name;
@@ -416,6 +417,8 @@ static int sock_attach_fd(struct socket
file->f_flags = O_RDWR;
file->f_pos = 0;
file->private_data = sock;
+ error = mnt_want_write(sock_mnt);
+ WARN_ON(error);
return 0;
}
_
Patches currently in -mm which might be from haveblue@xxxxxxxxxx are
origin.patch
git-acpi.patch
ro-bind-mounts-elevate-writer-count-for-custom-struct-file.patch
ro-bind-mounts-honor-r-w-changes-at-do_remount-time.patch
page-owner-tracking-leak-detector.patch
x86-e820-debugging.patch
-
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