A useful performance improvement for accessing virtual machine images via FUSE mount. See https://bugzilla.redhat.com/show_bug.cgi?id=1220173 for a use-case for glusterFS. Signed-off-by: Ravishankar N <ravishankar@xxxxxxxxxx> Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx> --- fs/fuse/file.c | 73 +++++++++++++++++++++++++++++++++++++++++------ fs/fuse/fuse_i.h | 3 ++ include/uapi/linux/fuse.h | 17 ++++++++++- 3 files changed, 84 insertions(+), 9 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 570ca40..aa03aab 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2231,20 +2231,77 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block) return err ? 0 : outarg.block; } +static loff_t fuse_lseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_mapping->host; + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_file *ff = file->private_data; + FUSE_ARGS(args); + struct fuse_lseek_in inarg = { + .fh = ff->fh, + .offset = offset, + .whence = whence + }; + struct fuse_lseek_out outarg; + int err; + + if (fc->no_lseek) + goto fallback; + + args.in.h.opcode = FUSE_LSEEK; + args.in.h.nodeid = ff->nodeid; + args.in.numargs = 1; + args.in.args[0].size = sizeof(inarg); + args.in.args[0].value = &inarg; + args.out.numargs = 1; + args.out.args[0].size = sizeof(outarg); + args.out.args[0].value = &outarg; + err = fuse_simple_request(fc, &args); + if (err) { + if (err == -ENOSYS) { + fc->no_lseek = 1; + goto fallback; + } + return err; + } + + return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes); + +fallback: + err = fuse_update_attributes(inode, NULL, file, NULL); + if (!err) + return generic_file_llseek(file, offset, whence); + else + return err; +} + static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence) { loff_t retval; struct inode *inode = file_inode(file); - /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */ - if (whence == SEEK_CUR || whence == SEEK_SET) - return generic_file_llseek(file, offset, whence); - - mutex_lock(&inode->i_mutex); - retval = fuse_update_attributes(inode, NULL, file, NULL); - if (!retval) + switch (whence) { + case SEEK_SET: + case SEEK_CUR: + /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */ retval = generic_file_llseek(file, offset, whence); - mutex_unlock(&inode->i_mutex); + break; + case SEEK_END: + mutex_lock(&inode->i_mutex); + retval = fuse_update_attributes(inode, NULL, file, NULL); + if (!retval) + retval = generic_file_llseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + break; + case SEEK_HOLE: + case SEEK_DATA: + mutex_lock(&inode->i_mutex); + retval = fuse_lseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + break; + default: + retval = -EINVAL; + } return retval; } diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 4051131..ce394b5 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -605,6 +605,9 @@ struct fuse_conn { /** Does the filesystem support asynchronous direct-IO submission? */ unsigned async_dio:1; + /** Is lseek not implemented by fs? */ + unsigned no_lseek:1; + /** The number of requests waiting for completion */ atomic_t num_waiting; diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index c9aca04..5974fae 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -102,6 +102,9 @@ * - add ctime and ctimensec to fuse_setattr_in * - add FUSE_RENAME2 request * - add FUSE_NO_OPEN_SUPPORT flag + * + * 7.24 + * - add FUSE_LSEEK for SEEK_HOLE and SEEK_DATA support */ #ifndef _LINUX_FUSE_H @@ -137,7 +140,7 @@ #define FUSE_KERNEL_VERSION 7 /** Minor version number of this interface */ -#define FUSE_KERNEL_MINOR_VERSION 23 +#define FUSE_KERNEL_MINOR_VERSION 24 /** The node ID of the root inode */ #define FUSE_ROOT_ID 1 @@ -358,6 +361,7 @@ enum fuse_opcode { FUSE_FALLOCATE = 43, FUSE_READDIRPLUS = 44, FUSE_RENAME2 = 45, + FUSE_LSEEK = 46, /* CUSE specific operations */ CUSE_INIT = 4096, @@ -758,4 +762,15 @@ struct fuse_notify_retrieve_in { /* Device ioctls: */ #define FUSE_DEV_IOC_CLONE _IOR(229, 0, uint32_t) +struct fuse_lseek_in { + uint64_t fh; + uint64_t offset; + uint32_t whence; + uint32_t padding; +}; + +struct fuse_lseek_out { + uint64_t offset; +}; + #endif /* _LINUX_FUSE_H */ -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
