From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from victor.provo.novell.com ([137.65.250.26]:48672 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752957AbaIBLu0 (ORCPT ); Tue, 2 Sep 2014 07:50:26 -0400 From: Filipe Manana To: linux-btrfs@vger.kernel.org Cc: Filipe Manana Subject: [PATCH v2] Btrfs: fix fsync data loss after a ranged fsync Date: Tue, 2 Sep 2014 13:50:12 +0100 Message-Id: <1409662212-12126-1-git-send-email-fdmanana@suse.com> In-Reply-To: <1409418015-30041-1-git-send-email-fdmanana@suse.com> References: <1409418015-30041-1-git-send-email-fdmanana@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: While we're doing a full fsync (when the inode has the flag BTRFS_INODE_NEEDS_FULL_SYNC set) that is ranged too (covers only a portion of the file), we might have ordered operations that are started before or while we're logging the inode and that fall outside the fsync range. Therefore when a full ranged fsync finishes don't remove every extent map from the list of modified extent maps - as for some of them, that fall outside our fsync range, their respective ordered operation hasn't finished yet, meaning the corresponding file extent item wasn't inserted into the fs/subvol tree yet and therefore we didn't log it, and we must let the next fast fsync (one that checks only the modified list) see this extent map and log a matching file extent item to the log btree and wait for its ordered operation to finish (if it's still ongoing). Signed-off-by: Filipe Manana --- V2: No code change, only updated the changelog and the comment, to make them more clear and accurate. fs/btrfs/file.c | 2 +- fs/btrfs/tree-log.c | 54 +++++++++++++++++++++++++++++++++++++++++++---------- fs/btrfs/tree-log.h | 2 ++ 3 files changed, 47 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 66c4076..e5534c1 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1979,7 +1979,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) btrfs_init_log_ctx(&ctx); - ret = btrfs_log_dentry_safe(trans, root, dentry, &ctx); + ret = btrfs_log_dentry_safe(trans, root, dentry, start, end, &ctx); if (ret < 0) { /* Fallthrough and commit/free transaction. */ ret = 1; diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 5a917a6..93d3c16 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -94,8 +94,10 @@ #define LOG_WALK_REPLAY_ALL 3 static int btrfs_log_inode(struct btrfs_trans_handle *trans, - struct btrfs_root *root, struct inode *inode, - int inode_only); + struct btrfs_root *root, struct inode *inode, + int inode_only, + const loff_t start, + const loff_t end); static int link_to_fixup_dir(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u64 objectid); @@ -3856,8 +3858,10 @@ process: * This handles both files and directories. */ static int btrfs_log_inode(struct btrfs_trans_handle *trans, - struct btrfs_root *root, struct inode *inode, - int inode_only) + struct btrfs_root *root, struct inode *inode, + int inode_only, + const loff_t start, + const loff_t end) { struct btrfs_path *path; struct btrfs_path *dst_path; @@ -4050,8 +4054,31 @@ log_extents: struct extent_map *em, *n; write_lock(&tree->lock); - list_for_each_entry_safe(em, n, &tree->modified_extents, list) + /* + * We can't just remove every em if we're called for a ranged + * fsync - that is, one that doesn't cover the whole possible + * file range (0 to LLONG_MAX). This is because we can have + * em's that fall outside the range we're logging and therefore + * their ordered operations haven't completed yet + * (btrfs_finish_ordered_io() not invoked yet). This means we + * didn't get their respective file extent item in the fs/subvol + * tree yet, and need to let the next fast fsync (one which + * consults the list of modified extent maps) find the em so + * that it logs a matching file extent item and waits for the + * respective ordered operation to complete (if it's still + * running). + * + * Removing every em outside the range we're logging would make + * the next fast fsync not log their matching file extent items, + * therefore making us lose data after a log replay. + */ + list_for_each_entry_safe(em, n, &tree->modified_extents, list) { + if (em->mod_start > end) + continue; + if (em->mod_start + em->mod_len <= start) + continue; list_del_init(&em->list); + } write_unlock(&tree->lock); } @@ -4158,7 +4185,10 @@ out: */ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, - struct dentry *parent, int exists_only, + struct dentry *parent, + const loff_t start, + const loff_t end, + int exists_only, struct btrfs_log_ctx *ctx) { int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL; @@ -4204,7 +4234,7 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (ret) goto end_no_trans; - ret = btrfs_log_inode(trans, root, inode, inode_only); + ret = btrfs_log_inode(trans, root, inode, inode_only, start, end); if (ret) goto end_trans; @@ -4232,7 +4262,8 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (BTRFS_I(inode)->generation > root->fs_info->last_trans_committed) { - ret = btrfs_log_inode(trans, root, inode, inode_only); + ret = btrfs_log_inode(trans, root, inode, inode_only, + 0, LLONG_MAX); if (ret) goto end_trans; } @@ -4266,13 +4297,15 @@ end_no_trans: */ int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct dentry *dentry, + const loff_t start, + const loff_t end, struct btrfs_log_ctx *ctx) { struct dentry *parent = dget_parent(dentry); int ret; ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, - 0, ctx); + start, end, 0, ctx); dput(parent); return ret; @@ -4509,6 +4542,7 @@ int btrfs_log_new_name(struct btrfs_trans_handle *trans, root->fs_info->last_trans_committed)) return 0; - return btrfs_log_inode_parent(trans, root, inode, parent, 1, NULL); + return btrfs_log_inode_parent(trans, root, inode, parent, 0, + LLONG_MAX, 1, NULL); } diff --git a/fs/btrfs/tree-log.h b/fs/btrfs/tree-log.h index 7f5b41b..e2e798a 100644 --- a/fs/btrfs/tree-log.h +++ b/fs/btrfs/tree-log.h @@ -59,6 +59,8 @@ int btrfs_free_log_root_tree(struct btrfs_trans_handle *trans, int btrfs_recover_log_trees(struct btrfs_root *tree_root); int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct dentry *dentry, + const loff_t start, + const loff_t end, struct btrfs_log_ctx *ctx); int btrfs_del_dir_entries_in_log(struct btrfs_trans_handle *trans, struct btrfs_root *root, -- 1.9.1