diff options
| -rw-r--r-- | fs/fuse/file.c | 43 | ||||
| -rw-r--r-- | include/uapi/linux/fuse.h | 3 |
2 files changed, 43 insertions, 3 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 89f4741728ba..d360d38ab616 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1563,14 +1563,47 @@ static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to) return res; } +static bool fuse_direct_write_extending_i_size(struct kiocb *iocb, + struct iov_iter *iter) +{ + struct inode *inode = file_inode(iocb->ki_filp); + + return iocb->ki_pos + iov_iter_count(iter) > i_size_read(inode); +} + static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct inode *inode = file_inode(iocb->ki_filp); + struct file *file = iocb->ki_filp; + struct fuse_file *ff = file->private_data; struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb); ssize_t res; + bool exclusive_lock = + !(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) || + iocb->ki_flags & IOCB_APPEND || + fuse_direct_write_extending_i_size(iocb, from); + + /* + * Take exclusive lock if + * - Parallel direct writes are disabled - a user space decision + * - Parallel direct writes are enabled and i_size is being extended. + * This might not be needed at all, but needs further investigation. + */ + if (exclusive_lock) + inode_lock(inode); + else { + inode_lock_shared(inode); + + /* A race with truncate might have come up as the decision for + * the lock type was done without holding the lock, check again. + */ + if (fuse_direct_write_extending_i_size(iocb, from)) { + inode_unlock_shared(inode); + inode_lock(inode); + exclusive_lock = true; + } + } - /* Don't allow parallel writes to the same file */ - inode_lock(inode); res = generic_write_checks(iocb, from); if (res > 0) { if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) { @@ -1581,7 +1614,10 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) fuse_write_update_attr(inode, iocb->ki_pos, res); } } - inode_unlock(inode); + if (exclusive_lock) + inode_unlock(inode); + else + inode_unlock_shared(inode); return res; } @@ -2931,6 +2967,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter) if (iov_iter_rw(iter) == WRITE) { fuse_write_update_attr(inode, pos, ret); + /* For extending writes we already hold exclusive lock */ if (ret < 0 && offset + count > i_size) fuse_do_truncate(file); } diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 39cfb343faa8..e3c54109bae9 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -200,6 +200,7 @@ * * 7.38 * - add FUSE_EXPIRE_ONLY flag to fuse_notify_inval_entry + * - add FOPEN_PARALLEL_DIRECT_WRITES */ #ifndef _LINUX_FUSE_H @@ -307,6 +308,7 @@ struct fuse_file_lock { * FOPEN_CACHE_DIR: allow caching this directory * FOPEN_STREAM: the file is stream-like (no file position at all) * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE) + * FOPEN_PARALLEL_DIRECT_WRITES: Allow concurrent direct writes on the same inode */ #define FOPEN_DIRECT_IO (1 << 0) #define FOPEN_KEEP_CACHE (1 << 1) @@ -314,6 +316,7 @@ struct fuse_file_lock { #define FOPEN_CACHE_DIR (1 << 3) #define FOPEN_STREAM (1 << 4) #define FOPEN_NOFLUSH (1 << 5) +#define FOPEN_PARALLEL_DIRECT_WRITES (1 << 6) /** * INIT request/reply flags |