Commit 27992ef8 authored by Bernd Schubert's avatar Bernd Schubert Committed by Miklos Szeredi
Browse files

fuse: Increase FUSE_NAME_MAX to PATH_MAX 

Our file system has a translation capability for S3-to-posix.
The current value of 1kiB is enough to cover S3 keys, but
does not allow encoding of %xx escape characters.
The limit is increased to (PATH_MAX - 1), as we need
3 x 1024 and that is close to PATH_MAX (4kB) already.
-1 is used as the terminating null is not included in the
length calculation.

Testing large file names was hard with libfuse/example file systems,
so I created a new memfs that does not have a 255 file name length
limitation.
https://github.com/libfuse/libfuse/pull/1077



The connection is initialized with FUSE_NAME_LOW_MAX, which
is set to the previous value of FUSE_NAME_MAX of 1024. With
FUSE_MIN_READ_BUFFER of 8192 that is enough for two file names
+ fuse headers.
When FUSE_INIT reply sets max_pages to a value > 1 we know
that fuse daemon supports request buffers of at least 2 pages
(+ header) and can therefore hold 2 x PATH_MAX file names - operations
like rename or link that need two file names are no issue then.

Signed-off-by: default avatarBernd Schubert <bschubert@ddn.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2412085d

fs/fuse/dev.c

+2 −2
Original line number Diff line number Diff line
@@ -1657,7 +1657,7 @@ static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size, 
		goto err;



	err = -ENAMETOOLONG;

	if (outarg.namelen > FUSE_NAME_MAX)

	if (outarg.namelen > fc->name_max)

		goto err;



	err = -EINVAL;
@@ -1706,7 +1706,7 @@ static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size, 
		goto err;



	err = -ENAMETOOLONG;

	if (outarg.namelen > FUSE_NAME_MAX)

	if (outarg.namelen > fc->name_max)

		goto err;



	err = -EINVAL;

fs/fuse/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -370,7 +370,7 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name 


	*inode = NULL;

	err = -ENAMETOOLONG;

	if (name->len > FUSE_NAME_MAX)

	if (name->len > fm->fc->name_max)

		goto out;

fs/fuse/fuse_i.h

+9 −2
Original line number Diff line number Diff line
@@ -38,8 +38,12 @@ 
/** Bias for fi->writectr, meaning new writepages must not be sent */

#define FUSE_NOWRITE INT_MIN



/** It could be as large as PATH_MAX, but would that have any uses? */

#define FUSE_NAME_MAX 1024

/** Maximum length of a filename, not including terminating null */



/* maximum, small enough for FUSE_MIN_READ_BUFFER*/

#define FUSE_NAME_LOW_MAX 1024

/* maximum, but needs a request buffer > FUSE_MIN_READ_BUFFER */

#define FUSE_NAME_MAX (PATH_MAX - 1)



/** Number of dentries for each connection in the control filesystem */

#define FUSE_CTL_NUM_DENTRIES 5
@@ -924,6 +928,9 @@ struct fuse_conn { 
	/** Version counter for evict inode */

	atomic64_t evict_ctr;



	/* maximum file name length */

	u32 name_max;



	/** Called on final put */

	void (*release)(struct fuse_conn *);

fs/fuse/inode.c

+8 −0
Original line number Diff line number Diff line
@@ -982,6 +982,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm, 
	fc->user_ns = get_user_ns(user_ns);

	fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;

	fc->max_pages_limit = fuse_max_pages_limit;

	fc->name_max = FUSE_NAME_LOW_MAX;

	fc->timeout.req_timeout = 0;



	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
@@ -1373,6 +1374,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, 
				fc->max_pages =

					min_t(unsigned int, fc->max_pages_limit,

					max_t(unsigned int, arg->max_pages, 1));



				/*

				 * PATH_MAX file names might need two pages for

				 * ops like rename

				 */

				if (fc->max_pages > 1)

					fc->name_max = FUSE_NAME_MAX;

			}

			if (IS_ENABLED(CONFIG_FUSE_DAX)) {

				if (flags & FUSE_MAP_ALIGNMENT &&