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authorJan Harkes <jaharkes@cs.cmu.edu>2019-07-16 16:28:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-16 19:23:22 -0700
commit7fa0a1da3dadfd9216df7745a1331fdaa0940d1c (patch)
tree78dac0029793a8831f7bff1df20a795efd020c16
parentb98cca444d287a63dd96df04af7fb9793567599e (diff)
coda: pass the host file in vma->vm_file on mmap
Patch series "Coda updates". The following patch series is a collection of various fixes for Coda, most of which were collected from linux-fsdevel or linux-kernel but which have as yet not found their way upstream. This patch (of 22): Various file systems expect that vma->vm_file points at their own file handle, several use file_inode(vma->vm_file) to get at their inode or use vma->vm_file->private_data. However the way Coda wrapped mmap on a host file broke this assumption, vm_file was still pointing at the Coda file and the host file systems would scribble over Coda's inode and private file data. This patch fixes the incorrect expectation and wraps vm_ops->open and vm_ops->close to allow Coda to track when the vm_area_struct is destroyed so we still release the reference on the Coda file handle at the right time. Link: http://lkml.kernel.org/r/0e850c6e59c0b147dc2dcd51a3af004c948c3697.1558117389.git.jaharkes@cs.cmu.edu Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Colin Ian King <colin.king@canonical.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: David Howells <dhowells@redhat.com> Cc: Fabian Frederick <fabf@skynet.be> Cc: Mikko Rapeli <mikko.rapeli@iki.fi> Cc: Sam Protsenko <semen.protsenko@linaro.org> Cc: Yann Droneaud <ydroneaud@opteya.com> Cc: Zhouyang Jia <jiazhouyang09@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/coda/file.c70
1 files changed, 68 insertions, 2 deletions
diff --git a/fs/coda/file.c b/fs/coda/file.c
index 1cbc1f2298ee..43d371551d2b 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -27,6 +27,13 @@
#include "coda_linux.h"
#include "coda_int.h"
+struct coda_vm_ops {
+ atomic_t refcnt;
+ struct file *coda_file;
+ const struct vm_operations_struct *host_vm_ops;
+ struct vm_operations_struct vm_ops;
+};
+
static ssize_t
coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
@@ -61,6 +68,34 @@ coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
return ret;
}
+static void
+coda_vm_open(struct vm_area_struct *vma)
+{
+ struct coda_vm_ops *cvm_ops =
+ container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
+
+ atomic_inc(&cvm_ops->refcnt);
+
+ if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
+ cvm_ops->host_vm_ops->open(vma);
+}
+
+static void
+coda_vm_close(struct vm_area_struct *vma)
+{
+ struct coda_vm_ops *cvm_ops =
+ container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
+
+ if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
+ cvm_ops->host_vm_ops->close(vma);
+
+ if (atomic_dec_and_test(&cvm_ops->refcnt)) {
+ vma->vm_ops = cvm_ops->host_vm_ops;
+ fput(cvm_ops->coda_file);
+ kfree(cvm_ops);
+ }
+}
+
static int
coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
{
@@ -68,6 +103,8 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
struct coda_inode_info *cii;
struct file *host_file;
struct inode *coda_inode, *host_inode;
+ struct coda_vm_ops *cvm_ops;
+ int ret;
cfi = CODA_FTOC(coda_file);
BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
@@ -76,6 +113,13 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
if (!host_file->f_op->mmap)
return -ENODEV;
+ if (WARN_ON(coda_file != vma->vm_file))
+ return -EIO;
+
+ cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
+ if (!cvm_ops)
+ return -ENOMEM;
+
coda_inode = file_inode(coda_file);
host_inode = file_inode(host_file);
@@ -89,6 +133,7 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
* the container file on us! */
else if (coda_inode->i_mapping != host_inode->i_mapping) {
spin_unlock(&cii->c_lock);
+ kfree(cvm_ops);
return -EBUSY;
}
@@ -97,7 +142,29 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
cfi->cfi_mapcount++;
spin_unlock(&cii->c_lock);
- return call_mmap(host_file, vma);
+ vma->vm_file = get_file(host_file);
+ ret = call_mmap(vma->vm_file, vma);
+
+ if (ret) {
+ /* if call_mmap fails, our caller will put coda_file so we
+ * should drop the reference to the host_file that we got.
+ */
+ fput(host_file);
+ kfree(cvm_ops);
+ } else {
+ /* here we add redirects for the open/close vm_operations */
+ cvm_ops->host_vm_ops = vma->vm_ops;
+ if (vma->vm_ops)
+ cvm_ops->vm_ops = *vma->vm_ops;
+
+ cvm_ops->vm_ops.open = coda_vm_open;
+ cvm_ops->vm_ops.close = coda_vm_close;
+ cvm_ops->coda_file = coda_file;
+ atomic_set(&cvm_ops->refcnt, 1);
+
+ vma->vm_ops = &cvm_ops->vm_ops;
+ }
+ return ret;
}
int coda_open(struct inode *coda_inode, struct file *coda_file)
@@ -207,4 +274,3 @@ const struct file_operations coda_file_operations = {
.fsync = coda_fsync,
.splice_read = generic_file_splice_read,
};
-