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fuse: fix wrong ff->iomode state changes from parallel dio write

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There is a confusion with fuse_file_uncached_io_{start,end} interface.
These helpers do two things when called from passthrough open()/release():
1. Take/drop negative refcount of fi->iocachectr (inode uncached io mode)
2. State change ff->iomode IOM_NONE <-> IOM_UNCACHED (file uncached open)

The calls from parallel dio write path need to take a reference on
fi->iocachectr, but they should not be changing ff->iomode state, because
in this case, the fi->iocachectr reference does not stick around until file
release().

Factor out helpers fuse_inode_uncached_io_{start,end}, to be used from
parallel dio write path and rename fuse_file_*cached_io_{start,end} helpers
to fuse_file_*cached_io_{open,release} to clarify the difference.

Fixes: 205c1d8026 ("fuse: allow parallel dio writes with FUSE_DIRECT_IO_ALLOW_MMAP")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2024-04-07 18:57:56 +03:00 committed by Miklos Szeredi
parent fec50db703
commit 4864a6dd83
4 changed files with 51 additions and 25 deletions
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12
fs/fuse/file.c
View File

@ -1362,7 +1362,7 @@ static void fuse_dio_lock(struct kiocb *iocb, struct iov_iter *from,
bool *exclusive)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct fuse_file *ff = iocb->ki_filp->private_data;
struct fuse_inode *fi = get_fuse_inode(inode);
*exclusive = fuse_dio_wr_exclusive_lock(iocb, from);
if (*exclusive) {
@ -1377,7 +1377,7 @@ static void fuse_dio_lock(struct kiocb *iocb, struct iov_iter *from,
* have raced, so check it again.
*/
if (fuse_io_past_eof(iocb, from) ||
fuse_file_uncached_io_start(inode, ff, NULL) != 0) {
fuse_inode_uncached_io_start(fi, NULL) != 0) {
inode_unlock_shared(inode);
inode_lock(inode);
*exclusive = true;
@ -1388,13 +1388,13 @@ static void fuse_dio_lock(struct kiocb *iocb, struct iov_iter *from,
static void fuse_dio_unlock(struct kiocb *iocb, bool exclusive)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct fuse_file *ff = iocb->ki_filp->private_data;
struct fuse_inode *fi = get_fuse_inode(inode);
if (exclusive) {
inode_unlock(inode);
} else {
/* Allow opens in caching mode after last parallel dio end */
fuse_file_uncached_io_end(inode, ff);
fuse_inode_uncached_io_end(fi);
inode_unlock_shared(inode);
}
}
@ -2574,8 +2574,10 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
* First mmap of direct_io file enters caching inode io mode.
* Also waits for parallel dio writers to go into serial mode
* (exclusive instead of shared lock).
* After first mmap, the inode stays in caching io mode until
* the direct_io file release.
*/
rc = fuse_file_cached_io_start(inode, ff);
rc = fuse_file_cached_io_open(inode, ff);
if (rc)
return rc;
}

7
fs/fuse/fuse_i.h
View File

@ -1394,9 +1394,10 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
struct dentry *dentry, struct fileattr *fa);
/* iomode.c */
int fuse_file_cached_io_start(struct inode *inode, struct fuse_file *ff);
int fuse_file_uncached_io_start(struct inode *inode, struct fuse_file *ff, struct fuse_backing *fb);
void fuse_file_uncached_io_end(struct inode *inode, struct fuse_file *ff);
int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff);
int fuse_inode_uncached_io_start(struct fuse_inode *fi,
struct fuse_backing *fb);
void fuse_inode_uncached_io_end(struct fuse_inode *fi);
int fuse_file_io_open(struct file *file, struct inode *inode);
void fuse_file_io_release(struct fuse_file *ff, struct inode *inode);

1
fs/fuse/inode.c
View File

@ -175,6 +175,7 @@ static void fuse_evict_inode(struct inode *inode)
}
}
if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
WARN_ON(fi->iocachectr != 0);
WARN_ON(!list_empty(&fi->write_files));
WARN_ON(!list_empty(&fi->queued_writes));
}

56
fs/fuse/iomode.c
View File

@ -21,12 +21,13 @@ static inline bool fuse_is_io_cache_wait(struct fuse_inode *fi)
}
/*
* Start cached io mode.
* Called on cached file open() and on first mmap() of direct_io file.
* Takes cached_io inode mode reference to be dropped on file release.
*
* Blocks new parallel dio writes and waits for the in-progress parallel dio
* writes to complete.
*/
int fuse_file_cached_io_start(struct inode *inode, struct fuse_file *ff)
int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff)
{
struct fuse_inode *fi = get_fuse_inode(inode);
@ -67,10 +68,9 @@ int fuse_file_cached_io_start(struct inode *inode, struct fuse_file *ff)
return 0;
}
static void fuse_file_cached_io_end(struct inode *inode, struct fuse_file *ff)
static void fuse_file_cached_io_release(struct fuse_file *ff,
struct fuse_inode *fi)
{
struct fuse_inode *fi = get_fuse_inode(inode);
spin_lock(&fi->lock);
WARN_ON(fi->iocachectr <= 0);
WARN_ON(ff->iomode != IOM_CACHED);
@ -82,9 +82,8 @@ static void fuse_file_cached_io_end(struct inode *inode, struct fuse_file *ff)
}
/* Start strictly uncached io mode where cache access is not allowed */
int fuse_file_uncached_io_start(struct inode *inode, struct fuse_file *ff, struct fuse_backing *fb)
int fuse_inode_uncached_io_start(struct fuse_inode *fi, struct fuse_backing *fb)
{
struct fuse_inode *fi = get_fuse_inode(inode);
struct fuse_backing *oldfb;
int err = 0;
@ -99,9 +98,7 @@ int fuse_file_uncached_io_start(struct inode *inode, struct fuse_file *ff, struc
err = -ETXTBSY;
goto unlock;
}
WARN_ON(ff->iomode != IOM_NONE);
fi->iocachectr--;
ff->iomode = IOM_UNCACHED;
/* fuse inode holds a single refcount of backing file */
if (!oldfb) {
@ -115,15 +112,29 @@ unlock:
return err;
}
void fuse_file_uncached_io_end(struct inode *inode, struct fuse_file *ff)
/* Takes uncached_io inode mode reference to be dropped on file release */
static int fuse_file_uncached_io_open(struct inode *inode,
struct fuse_file *ff,
struct fuse_backing *fb)
{
struct fuse_inode *fi = get_fuse_inode(inode);
int err;
err = fuse_inode_uncached_io_start(fi, fb);
if (err)
return err;
WARN_ON(ff->iomode != IOM_NONE);
ff->iomode = IOM_UNCACHED;
return 0;
}
void fuse_inode_uncached_io_end(struct fuse_inode *fi)
{
struct fuse_backing *oldfb = NULL;
spin_lock(&fi->lock);
WARN_ON(fi->iocachectr >= 0);
WARN_ON(ff->iomode != IOM_UNCACHED);
ff->iomode = IOM_NONE;
fi->iocachectr++;
if (!fi->iocachectr) {
wake_up(&fi->direct_io_waitq);
@ -134,6 +145,15 @@ void fuse_file_uncached_io_end(struct inode *inode, struct fuse_file *ff)
fuse_backing_put(oldfb);
}
/* Drop uncached_io reference from passthrough open */
static void fuse_file_uncached_io_release(struct fuse_file *ff,
struct fuse_inode *fi)
{
WARN_ON(ff->iomode != IOM_UNCACHED);
ff->iomode = IOM_NONE;
fuse_inode_uncached_io_end(fi);
}
/*
* Open flags that are allowed in combination with FOPEN_PASSTHROUGH.
* A combination of FOPEN_PASSTHROUGH and FOPEN_DIRECT_IO means that read/write
@ -163,7 +183,7 @@ static int fuse_file_passthrough_open(struct inode *inode, struct file *file)
return PTR_ERR(fb);
/* First passthrough file open denies caching inode io mode */
err = fuse_file_uncached_io_start(inode, ff, fb);
err = fuse_file_uncached_io_open(inode, ff, fb);
if (!err)
return 0;
@ -216,7 +236,7 @@ int fuse_file_io_open(struct file *file, struct inode *inode)
if (ff->open_flags & FOPEN_PASSTHROUGH)
err = fuse_file_passthrough_open(inode, file);
else
err = fuse_file_cached_io_start(inode, ff);
err = fuse_file_cached_io_open(inode, ff);
if (err)
goto fail;
@ -236,8 +256,10 @@ fail:
/* No more pending io and no new io possible to inode via open/mmapped file */
void fuse_file_io_release(struct fuse_file *ff, struct inode *inode)
{
struct fuse_inode *fi = get_fuse_inode(inode);
/*
* Last parallel dio close allows caching inode io mode.
* Last passthrough file close allows caching inode io mode.
* Last caching file close exits caching inode io mode.
*/
switch (ff->iomode) {
@ -245,10 +267,10 @@ void fuse_file_io_release(struct fuse_file *ff, struct inode *inode)
/* Nothing to do */
break;
case IOM_UNCACHED:
fuse_file_uncached_io_end(inode, ff);
fuse_file_uncached_io_release(ff, fi);
break;
case IOM_CACHED:
fuse_file_cached_io_end(inode, ff);
fuse_file_cached_io_release(ff, fi);
break;
}
}