[Devel] [PATCH VZ10 v3] fs/fuse: align fuse_create_open()'s open path with fuse_open()
Liu Kui
kui.liu at virtuozzo.com
Fri Jun 26 17:32:53 MSK 2026
fuse_create_open()'s close_wait branch was not correct; in particular the
fput() in its error path was wrong. fuse_open()'s close_wait branch should
apply instead.
The two sites differ in one important way, though: fuse_open() runs the
block before FMODE_OPENED is set, where fuse_sync_release() is the correct
cleanup on error, whereas fuse_create_open() runs it after FMODE_OPENED is
set, where fuse_sync_release() must not be called. To unify them, refactor
the sequence into fuse_open_close_wait() and call it from
fuse_finish_open(), so the block runs before FMODE_OPENED on both paths.
The error then propagates to the caller and the block itself no longer
needs to call fuse_sync_release().
Add a per-open FUSE_S_INODE_LOCKED flag telling fuse_open_close_wait() that
the caller already holds the inode lock, so it is not re-acquired and
deadlocks on the atomic O_TRUNC path.
https://virtuozzo.atlassian.net/browse/VSTOR-136027
Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
---
Changes in v3:
- Call fuse_open_close_wait() from fuse_finish_open() instead of from
the fuse_open() and fuse_create_open() call sites, so the sequence
runs before FMODE_OPENED is set on both paths.
- Drop the fuse_sync_release() call inside fuse_open_close_wait(); the
error now propagates to the caller, which releases the file before
FMODE_OPENED is set.
- Make fuse_open_close_wait() static and drop its fuse_i.h prototype.
- Acquire the inode lock in fuse_open_close_wait() only when the caller
does not already hold it, tracked by a per-open FUSE_S_INODE_LOCKED
flag, so the atomic O_TRUNC path (which already holds it) does not
self-deadlock.
Changes in v2:
- Factor the close_wait open branch into fuse_open_close_wait();
call it from both fuse_open() and fuse_create_open() instead of
duplicating the block in each.
- Use fuse_sync_release() on the close_wait error path for both
callers. It is functionally equivalent to fuse_release_common()
used in fuse_open().
fs/fuse/dir.c | 17 -----------
fs/fuse/file.c | 73 ++++++++++++++++++++++++++++--------------------
fs/fuse/fuse_i.h | 4 ++-
3 files changed, 46 insertions(+), 48 deletions(-)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 45ee4f1e4b68..9799c2b6eb4d 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -722,23 +722,6 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
invalidate_inode_pages2(inode->i_mapping);
}
- if (fm->fc->close_wait) {
- struct fuse_inode *fi = get_fuse_inode(inode);
- bool need_open;
-
- inode_lock(inode);
- spin_lock(&fi->lock);
- need_open = (++fi->num_openers == 1);
- spin_unlock(&fi->lock);
-
- if (need_open && fm->fc->kio.op && fm->fc->kio.op->file_open) {
- err = fm->fc->kio.op->file_open(file, inode);
- if (err)
- fput(file);
- }
- inode_unlock(inode);
- }
-
return err;
out_free_ff:
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 58202a96517e..8750cbdf0596 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -286,6 +286,43 @@ static void fuse_link_rw_file(struct file *file)
spin_unlock(&fi->lock);
}
+static int fuse_open_close_wait(struct inode *inode, struct file *file)
+{
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ struct fuse_file *ff = file->private_data;
+ /* the caller already holds the inode lock (e.g. truncate open) */
+ bool locked = test_and_clear_bit(FUSE_S_INODE_LOCKED, &ff->ff_state);
+ int err = 0;
+
+ if (!locked)
+ inode_lock(inode);
+ spin_lock(&fi->lock);
+
+ if (++fi->num_openers == 1 || fi->i_size_unstable) {
+ fi->i_size_unstable = 1;
+ fi->inval_mask = ~0;
+ spin_unlock(&fi->lock);
+ err = fuse_update_attributes(inode, file, ~0);
+
+ if (!err && fc->kio.op && fc->kio.op->file_open)
+ err = fc->kio.op->file_open(file, inode);
+
+ spin_lock(&fi->lock);
+ fi->i_size_unstable = 0;
+ if (err)
+ fi->num_openers--;
+ }
+
+ file->f_mode |= FMODE_NOWAIT;
+
+ spin_unlock(&fi->lock);
+ if (!locked)
+ inode_unlock(inode);
+
+ return err;
+}
+
int fuse_finish_open(struct inode *inode, struct file *file)
{
struct fuse_file *ff = file->private_data;
@@ -319,6 +356,9 @@ int fuse_finish_open(struct inode *inode, struct file *file)
*/
if (!test_bit(FUSE_S_FAIL_IMMEDIATELY, &ff->ff_state))
err = fuse_wait_on_inval_files(inode);
+
+ if (!err)
+ err = fuse_open_close_wait(inode, file);
}
return err;
@@ -378,6 +418,9 @@ static int fuse_open(struct inode *inode, struct file *file)
err = fuse_do_open(fm, get_node_id(inode), file, false);
if (!err) {
ff = file->private_data;
+ /* tell fuse_open_close_wait() we already hold the inode lock */
+ if ((is_wb_truncate || dax_truncate) && fc->close_wait)
+ set_bit(FUSE_S_INODE_LOCKED, &ff->ff_state);
err = fuse_finish_open(inode, file);
if (err)
fuse_sync_release(fi, ff, file->f_flags);
@@ -399,36 +442,6 @@ static int fuse_open(struct inode *inode, struct file *file)
if (is_wb_truncate || dax_truncate)
inode_unlock(inode);
- if (!err && fc->close_wait) {
- inode_lock(inode);
- spin_lock(&fi->lock);
-
- if (++fi->num_openers == 1 || fi->i_size_unstable) {
- fi->i_size_unstable = 1;
- fi->inval_mask = ~0;
- spin_unlock(&fi->lock);
- err = fuse_update_attributes(inode, file, ~0);
-
- if (!err && fc->kio.op && fc->kio.op->file_open)
- err = fc->kio.op->file_open(file, inode);
-
- spin_lock(&fi->lock);
- fi->i_size_unstable = 0;
- if (err)
- fi->num_openers--;
- }
-
- file->f_mode |= FMODE_NOWAIT;
-
- spin_unlock(&fi->lock);
- inode_unlock(inode);
-
- if (err) {
- fuse_release_common(file, false);
- return err;
- }
- }
-
return err;
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a834a5b4dfe2..53dfcb495ca0 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -327,7 +327,9 @@ struct fuse_file {
enum {
/** Any fops on given ff should fail immediately */
FUSE_S_FAIL_IMMEDIATELY = 0,
- FUSE_S_CLOSING = 1
+ FUSE_S_CLOSING = 1,
+ /** The open path already holds the inode lock (close_wait) */
+ FUSE_S_INODE_LOCKED = 2,
};
/** One input argument of a request */
--
2.50.1 (Apple Git-155)
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