[PATCH v4 0/4] fs/9p: fix mmap regression

[PATCH v4 0/4] fs/9p: fix mmap regression

[Eric Van Hensbergen]

This series attempts to fix a reported exception with mmap
on newer kernels. 

Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reported-by: Robert Schwebel <r.schwebel@pengutronix.de>
Closes: https://lore.kernel.org/v9fs/ZK25XZ%2BGpR3KHIB%2F@pengutronix.de
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
Changes in v4:
- Another attempt to fix tags for regression and stable, sorry for the
  noise.
- Link to v3: https://lore.kernel.org/r/20230716-fixes-overly-restrictive-mmap-v3-0-769791f474fd@kernel.org

Changes in v3:
- Clarify debug print to read-only mmap mode versus no mmap mode in
  v9fs_file_mmap
- Fix suggested regression tags and propagate across series
- Link to v2: https://lore.kernel.org/r/20230716-fixes-overly-restrictive-mmap-v2-0-147d6b93f699@kernel.org

Changes in v2:
- fix requested changes in commit messages
- add patch to remove unnecessary invalidate_inode_pages in mmap readonly path
- Link to v1: https://lore.kernel.org/r/20230716-fixes-overly-restrictive-mmap-v1-0-0683b283b932@kernel.org

---
Eric Van Hensbergen (4):
      fs/9p: remove unnecessary and overrestrictive check
      fs/9p: fix typo in comparison logic for cache mode
      fs/9p: fix type mismatch in file cache mode helper
      fs/9p: remove unnecessary invalidate_inode_pages2

 fs/9p/fid.h      | 6 +++---
 fs/9p/vfs_file.c | 5 +----
 2 files changed, 4 insertions(+), 7 deletions(-)
---
base-commit: 95f41d87810083d8b3dedcce46a4e356cf4a9673
change-id: 20230716-fixes-overly-restrictive-mmap-30a23501e787

Best regards,
-- 
Eric Van Hensbergen <ericvh@kernel.org>

[PATCH v4 1/4] fs/9p: remove unnecessary and overrestrictive check

[Eric Van Hensbergen]

This eliminates a check for shared that was overrestrictive and
prevented read-only mmaps when writeback caches weren't enabled.

Cc: stable@vger.kernel.org
Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reported-by: Robert Schwebel <r.schwebel@pengutronix.de>
Closes: https://lore.kernel.org/v9fs/ZK25XZ%2BGpR3KHIB%2F@pengutronix.de
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
 fs/9p/vfs_file.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 2996fb00387f..9b61b480a9b0 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -505,9 +505,7 @@ v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 	p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
 
 	if (!(v9ses->cache & CACHE_WRITEBACK)) {
-		p9_debug(P9_DEBUG_CACHE, "(no mmap mode)");
-		if (vma->vm_flags & VM_MAYSHARE)
-			return -ENODEV;
+		p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
 		invalidate_inode_pages2(filp->f_mapping);
 		return generic_file_readonly_mmap(filp, vma);
 	}

-- 
2.39.2

[PATCH v4 2/4] fs/9p: fix typo in comparison logic for cache mode

[Eric Van Hensbergen]

There appears to be a typo in the comparison statement for the logic
which sets a file's cache mode based on mount flags.

Cc: stable@vger.kernel.org
Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
 fs/9p/fid.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index 0c51889a60b3..297c2c377e3d 100644
--- a/fs/9p/fid.h
+++ b/fs/9p/fid.h
@@ -57,7 +57,7 @@ static inline void v9fs_fid_add_modes(struct p9_fid *fid, int s_flags,
 	   (s_flags & V9FS_DIRECT_IO) || (f_flags & O_DIRECT)) {
 		fid->mode |= P9L_DIRECT; /* no read or write cache */
 	} else if ((!(s_cache & CACHE_WRITEBACK)) ||
-				(f_flags & O_DSYNC) | (s_flags & V9FS_SYNC)) {
+				(f_flags & O_DSYNC) || (s_flags & V9FS_SYNC)) {
 		fid->mode |= P9L_NOWRITECACHE;
 	}
 }

-- 
2.39.2

[PATCH v4 3/4] fs/9p: fix type mismatch in file cache mode helper

[Eric Van Hensbergen]

There were two flags (s_flags and s_cache) which had incorrect signed
type in the parameters of the file cache mode helper function.

Cc: stable@vger.kernel.org
Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
 fs/9p/fid.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index 297c2c377e3d..29281b7c3887 100644
--- a/fs/9p/fid.h
+++ b/fs/9p/fid.h
@@ -46,8 +46,8 @@ static inline struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
  * NOTE: these are set after open so only reflect 9p client not
  * underlying file system on server.
  */
-static inline void v9fs_fid_add_modes(struct p9_fid *fid, int s_flags,
-	int s_cache, unsigned int f_flags)
+static inline void v9fs_fid_add_modes(struct p9_fid *fid, unsigned int s_flags,
+	unsigned int s_cache, unsigned int f_flags)
 {
 	if (fid->qid.type != P9_QTFILE)
 		return;

-- 
2.39.2

[PATCH v4 4/4] fs/9p: remove unnecessary invalidate_inode_pages2

[Eric Van Hensbergen]

There was an invalidate_inode_pages2 added to readonly mmap path
that is unnecessary since that path is only entered when writeback
cache is disabled on mount.

Cc: stable@vger.kernel.org
Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
 fs/9p/vfs_file.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 9b61b480a9b0..11cd8d23f6f2 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -506,7 +506,6 @@ v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 
 	if (!(v9ses->cache & CACHE_WRITEBACK)) {
 		p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
-		invalidate_inode_pages2(filp->f_mapping);
 		return generic_file_readonly_mmap(filp, vma);
 	}
 

-- 
2.39.2