| Message ID | 20241213-fuse_name_max-limit-6-13-v2-2-39fec5253632@ddn.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fuse: Increase FUSE_NAME_MAX limit | expand |
On 12/14/24 12:01 AM, Bernd Schubert wrote: > 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 > > Signed-off-by: Bernd Schubert <bschubert@ddn.com> LGTM. Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com> > --- > fs/fuse/fuse_i.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index 74744c6f286003251564d1235f4d2ca8654d661b..a47a0ba3ccad7d9cbf105fcae728712d5721850c 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -38,8 +38,8 @@ > /** 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 */ > +#define FUSE_NAME_MAX (PATH_MAX - 1) > > /** Number of dentries for each connection in the control filesystem */ > #define FUSE_CTL_NUM_DENTRIES 5 >
Large file-names (up to 4095) may cause the encoded input of FUSE_SYMLINK and FUSE_RENAME to exceed the default value of FUSE_MIN_READ_BUFFER (8192). Whoever implements such a FUSE file-system should keep this in mind. - Shachar. On Fri, Dec 13, 2024 at 6:02 PM Bernd Schubert <bschubert@ddn.com> wrote: > > 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 > > Signed-off-by: Bernd Schubert <bschubert@ddn.com> > --- > fs/fuse/fuse_i.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index 74744c6f286003251564d1235f4d2ca8654d661b..a47a0ba3ccad7d9cbf105fcae728712d5721850c 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -38,8 +38,8 @@ > /** 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 */ > +#define FUSE_NAME_MAX (PATH_MAX - 1) > > /** Number of dentries for each connection in the control filesystem */ > #define FUSE_CTL_NUM_DENTRIES 5 > > -- > 2.43.0 >
On 12/14/24 03:07, Jingbo Xu wrote: > > > On 12/14/24 12:01 AM, Bernd Schubert wrote: >> 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 >> >> Signed-off-by: Bernd Schubert <bschubert@ddn.com> > > LGTM. > > Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com> > Thank you! I didn't add your reviewed-by yet, as I added some changes to address Shachars concern about operations that need two hold two file names, but fuse server might use FUSE_MIN_READ_BUFFER. Thanks, Bernd
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 74744c6f286003251564d1235f4d2ca8654d661b..a47a0ba3ccad7d9cbf105fcae728712d5721850c 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -38,8 +38,8 @@ /** 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 */ +#define FUSE_NAME_MAX (PATH_MAX - 1) /** Number of dentries for each connection in the control filesystem */ #define FUSE_CTL_NUM_DENTRIES 5
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 Signed-off-by: Bernd Schubert <bschubert@ddn.com> --- fs/fuse/fuse_i.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)