From 67d756c27ac4f4576dee313579724bd8711bc75e Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Fri, 11 May 2018 11:49:30 -0400 Subject: ovl: Fix ovl_getattr() to get number of blocks from lower If an inode has been copied up metadata only, then we need to query the number of blocks from lower and fill up the stat->st_blocks. We need to be careful about races where we are doing stat on one cpu and data copy up is taking place on other cpu. We want to return stat->st_blocks either from lower or stable upper and not something in between. Hence, ovl_has_upperdata() is called first to figure out whether block reporting will take place from lower or upper. We now support metacopy dentries in middle layer. That means number of blocks reporting needs to come from lowest data dentry and this could be different from lower dentry. Hence we end up making a separate vfs_getxattr() call for metacopy dentries to get number of blocks. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/inode.c | 35 ++++++++++++++++++++++++++++++++++- fs/overlayfs/overlayfs.h | 1 + fs/overlayfs/util.c | 16 ++++++++++++++++ 3 files changed, 51 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index d3e65d2a1b83..2a5a38c81961 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -145,6 +145,9 @@ int ovl_getattr(const struct path *path, struct kstat *stat, bool samefs = ovl_same_sb(dentry->d_sb); struct ovl_layer *lower_layer = NULL; int err; + bool metacopy_blocks = false; + + metacopy_blocks = ovl_is_metacopy_dentry(dentry); type = ovl_path_real(dentry, &realpath); old_cred = ovl_override_creds(dentry->d_sb); @@ -166,7 +169,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat, lower_layer = ovl_layer_lower(dentry); } else if (OVL_TYPE_ORIGIN(type)) { struct kstat lowerstat; - u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0); + u32 lowermask = STATX_INO | STATX_BLOCKS | + (!is_dir ? STATX_NLINK : 0); ovl_path_lower(dentry, &realpath); err = vfs_getattr(&realpath, &lowerstat, @@ -195,6 +199,35 @@ int ovl_getattr(const struct path *path, struct kstat *stat, stat->ino = lowerstat.ino; lower_layer = ovl_layer_lower(dentry); } + + /* + * If we are querying a metacopy dentry and lower + * dentry is data dentry, then use the blocks we + * queried just now. We don't have to do additional + * vfs_getattr(). If lower itself is metacopy, then + * additional vfs_getattr() is unavoidable. + */ + if (metacopy_blocks && + realpath.dentry == ovl_dentry_lowerdata(dentry)) { + stat->blocks = lowerstat.blocks; + metacopy_blocks = false; + } + } + + if (metacopy_blocks) { + /* + * If lower is not same as lowerdata or if there was + * no origin on upper, we can end up here. + */ + struct kstat lowerdatastat; + u32 lowermask = STATX_BLOCKS; + + ovl_path_lowerdata(dentry, &realpath); + err = vfs_getattr(&realpath, &lowerdatastat, + lowermask, flags); + if (err) + goto out; + stat->blocks = lowerdatastat.blocks; } } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index deda94381aac..de80250b379f 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -271,6 +271,7 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked); void ovl_nlink_end(struct dentry *dentry, bool locked); int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir); int ovl_check_metacopy_xattr(struct dentry *dentry); +bool ovl_is_metacopy_dentry(struct dentry *dentry); static inline bool ovl_is_impuredir(struct dentry *dentry) { diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 7c7b95d5da1f..4f9c2ecee74c 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -825,3 +825,19 @@ out: pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res); return res; } + +bool ovl_is_metacopy_dentry(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + if (!d_is_reg(dentry)) + return false; + + if (ovl_dentry_upper(dentry)) { + if (!ovl_has_upperdata(d_inode(dentry))) + return true; + return false; + } + + return (oe->numlower > 1); +} -- cgit v1.2.3