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authorDavid Howells <dhowells@redhat.com>2021-06-17 15:09:21 +0300
committerDavid Howells <dhowells@redhat.com>2023-12-28 12:45:24 +0300
commit938e13a73b244278a3777f38fa915bd239b2efd2 (patch)
treec1625777ab2962f8cbefcc993b2b9b3124bc1417 /fs/netfs
parent153a9961b551101cd38e94e26cd92fbfd198b19b (diff)
downloadlinux-938e13a73b244278a3777f38fa915bd239b2efd2.tar.xz
netfs: Implement buffered write API
Institute a netfs write helper, netfs_file_write_iter(), to be pointed at by the network filesystem ->write_iter() call. Make it handled buffered writes by calling the previously defined netfs_perform_write() to copy the source data into the pagecache. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org
Diffstat (limited to 'fs/netfs')
-rw-r--r--fs/netfs/buffered_write.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index b76688e98f81..f244123ab568 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -333,3 +333,86 @@ error_folio_unlock:
goto out;
}
EXPORT_SYMBOL(netfs_perform_write);
+
+/**
+ * netfs_buffered_write_iter_locked - write data to a file
+ * @iocb: IO state structure (file, offset, etc.)
+ * @from: iov_iter with data to write
+ * @netfs_group: Grouping for dirty pages (eg. ceph snaps).
+ *
+ * This function does all the work needed for actually writing data to a
+ * file. It does all basic checks, removes SUID from the file, updates
+ * modification times and calls proper subroutines depending on whether we
+ * do direct IO or a standard buffered write.
+ *
+ * The caller must hold appropriate locks around this function and have called
+ * generic_write_checks() already. The caller is also responsible for doing
+ * any necessary syncing afterwards.
+ *
+ * This function does *not* take care of syncing data in case of O_SYNC write.
+ * A caller has to handle it. This is mainly due to the fact that we want to
+ * avoid syncing under i_rwsem.
+ *
+ * Return:
+ * * number of bytes written, even for truncated writes
+ * * negative error code if no data has been written at all
+ */
+ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
+ struct netfs_group *netfs_group)
+{
+ struct file *file = iocb->ki_filp;
+ ssize_t ret;
+
+ trace_netfs_write_iter(iocb, from);
+
+ ret = file_remove_privs(file);
+ if (ret)
+ return ret;
+
+ ret = file_update_time(file);
+ if (ret)
+ return ret;
+
+ return netfs_perform_write(iocb, from, netfs_group);
+}
+EXPORT_SYMBOL(netfs_buffered_write_iter_locked);
+
+/**
+ * netfs_file_write_iter - write data to a file
+ * @iocb: IO state structure
+ * @from: iov_iter with data to write
+ *
+ * Perform a write to a file, writing into the pagecache if possible and doing
+ * an unbuffered write instead if not.
+ *
+ * Return:
+ * * Negative error code if no data has been written at all of
+ * vfs_fsync_range() failed for a synchronous write
+ * * Number of bytes written, even for truncated writes
+ */
+ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ struct netfs_inode *ictx = netfs_inode(inode);
+ ssize_t ret;
+
+ _enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode));
+
+ if ((iocb->ki_flags & IOCB_DIRECT) ||
+ test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags))
+ return netfs_unbuffered_write_iter(iocb, from);
+
+ ret = netfs_start_io_write(inode);
+ if (ret < 0)
+ return ret;
+
+ ret = generic_write_checks(iocb, from);
+ if (ret > 0)
+ ret = netfs_buffered_write_iter_locked(iocb, from, NULL);
+ netfs_end_io_write(inode);
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+ return ret;
+}
+EXPORT_SYMBOL(netfs_file_write_iter);