renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-16 09:13:55 +08:00
Code

fuse: Trust kernel i_size only

Browse Source 
Make fuse think that when writeback is on the inode's i_size is always
up-to-date and not update it with the value received from the userspace.
This is done because the page cache code may update i_size without letting
the FS know.

This assumption implies fixing the previously introduced short-read helper --
when a short read occurs the 'hole' is filled with zeroes.

fuse_file_fallocate() is also fixed because now we should keep i_size up to
date, so it must be updated if FUSE_FALLOCATE request succeeded.

Signed-off-by: Maxim V. Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Pavel Emelyanov 2013-10-10 17:10:46 +04:00 committed by Miklos Szeredi
parent d5cd66c58e
commit 8373200b12
3 changed files with 39 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/fuse/dir.c
View File

@ -839,6 +839,11 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
struct kstat *stat)
{
unsigned int blkbits;
struct fuse_conn *fc = get_fuse_conn(inode);
/* see the comment in fuse_change_attributes() */
if (fc->writeback_cache && S_ISREG(inode->i_mode))
attr->size = i_size_read(inode);
stat->dev = inode->i_sb->s_dev;
stat->ino = attr->ino;
@ -1580,6 +1585,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
struct fuse_setattr_in inarg;
struct fuse_attr_out outarg;
bool is_truncate = false;
bool is_wb = fc->writeback_cache;
loff_t oldsize;
int err;
@ -1651,7 +1657,9 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
fuse_change_attributes_common(inode, &outarg.attr,
attr_timeout(&outarg));
oldsize = inode->i_size;
i_size_write(inode, outarg.attr.size);
/* see the comment in fuse_change_attributes() */
if (!is_wb || is_truncate || !S_ISREG(inode->i_mode))
i_size_write(inode, outarg.attr.size);
if (is_truncate) {
/* NOTE: this may release/reacquire fc->lock */
@ -1663,7 +1671,8 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
* Only call invalidate_inode_pages2() after removing
* FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock.
*/
if (S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
if ((is_truncate || !is_wb) &&
S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
truncate_pagecache(inode, outarg.attr.size);
invalidate_inode_pages2(inode->i_mapping);
}

21
fs/fuse/file.c
View File

@ -675,9 +675,26 @@ static void fuse_short_read(struct fuse_req *req, struct inode *inode,
u64 attr_ver)
{
size_t num_read = req->out.args[0].size;
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = page_offset(req->pages[0]) + num_read;
fuse_read_update_size(inode, pos, attr_ver);
if (fc->writeback_cache) {
/*
* A hole in a file. Some data after the hole are in page cache,
* but have not reached the client fs yet. So, the hole is not
* present there.
*/
int i;
int start_idx = num_read >> PAGE_CACHE_SHIFT;
size_t off = num_read & (PAGE_CACHE_SIZE - 1);
for (i = start_idx; i < req->num_pages; i++) {
zero_user_segment(req->pages[i], off, PAGE_CACHE_SIZE);
off = 0;
}
} else {
loff_t pos = page_offset(req->pages[0]) + num_read;
fuse_read_update_size(inode, pos, attr_ver);
}
}
static int fuse_readpage(struct file *file, struct page *page)

11
fs/fuse/inode.c
View File

@ -197,6 +197,7 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
bool is_wb = fc->writeback_cache;
loff_t oldsize;
struct timespec old_mtime;
@ -211,10 +212,16 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
fuse_change_attributes_common(inode, attr, attr_valid);
oldsize = inode->i_size;
i_size_write(inode, attr->size);
/*
* In case of writeback_cache enabled, the cached writes beyond EOF
* extend local i_size without keeping userspace server in sync. So,
* attr->size coming from server can be stale. We cannot trust it.
*/
if (!is_wb || !S_ISREG(inode->i_mode))
i_size_write(inode, attr->size);
spin_unlock(&fc->lock);
if (S_ISREG(inode->i_mode)) {
if (!is_wb && S_ISREG(inode->i_mode)) {
bool inval = false;
if (oldsize != attr->size) {