From 728fbc0e10b7f3ce2ee043b32e3453fd5201c055 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Tue, 20 Jun 2017 07:05:47 -0500 Subject: [PATCH] ext4: nowait aio support Return EAGAIN if any of the following checks fail for direct I/O: + i_rwsem is lockable + Writing beyond end of file (will trigger allocation) + Blocks are not allocated at the write location Signed-off-by: Goldwyn Rodrigues Reviewed-by: Jan Kara Signed-off-by: Jens Axboe --- fs/ext4/file.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 02ce7e7bbdf5..58e2eeaa0bc4 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -37,7 +37,11 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; - inode_lock_shared(inode); + if (!inode_trylock_shared(inode)) { + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + inode_lock_shared(inode); + } /* * Recheck under inode lock - at this point we are sure it cannot * change anymore @@ -179,7 +183,11 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; - inode_lock(inode); + if (!inode_trylock(inode)) { + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + inode_lock(inode); + } ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; @@ -216,7 +224,12 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) return ext4_dax_write_iter(iocb, from); #endif - inode_lock(inode); + if (!inode_trylock(inode)) { + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + inode_lock(inode); + } + ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; @@ -235,9 +248,15 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) iocb->private = &overwrite; /* Check whether we do a DIO overwrite or not */ - if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio && - ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) - overwrite = 1; + if (o_direct && !unaligned_aio) { + if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) { + if (ext4_should_dioread_nolock(inode)) + overwrite = 1; + } else if (iocb->ki_flags & IOCB_NOWAIT) { + ret = -EAGAIN; + goto out; + } + } ret = __generic_file_write_iter(iocb, from); inode_unlock(inode); @@ -435,6 +454,10 @@ static int ext4_file_open(struct inode * inode, struct file * filp) if (ret < 0) return ret; } + + /* Set the flags to support nowait AIO */ + filp->f_mode |= FMODE_AIO_NOWAIT; + return dquot_file_open(inode, filp); }