From: David Howells Date: Wed, 11 Feb 2015 13:40:17 +0000 (+0000) Subject: VFS: Add owner-filesystem positive/negative dentry checks X-Git-Tag: omap-for-v4.1/fixes-rc1~116^2~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=525d27b23555419e0e7b73fb6e78d4d678cb4f32;p=pandora-kernel.git VFS: Add owner-filesystem positive/negative dentry checks Supply two functions to test whether a filesystem's own dentries are positive or negative (d_really_is_positive() and d_really_is_negative()). The problem is that the DCACHE_ENTRY_TYPE field of dentry->d_flags may be overridden by the union part of a layered filesystem and isn't thus necessarily indicative of the type of dentry. Normally, this would involve a negative dentry (ie. ->d_inode == NULL) having ->d_layer.lower pointed to a lower layer dentry, DCACHE_PINNING_LOWER set and the DCACHE_ENTRY_TYPE field set to something other than DCACHE_MISS_TYPE - but it could also involve, say, a DCACHE_SPECIAL_TYPE being overridden to DCACHE_WHITEOUT_TYPE if a 0,0 chardev is detected in the top layer. However, inside a filesystem, when that fs is looking at its own dentries, it probably wants to know if they are really negative or not - and doesn't care about the fallthrough bits used by the union. To this end, a filesystem should normally use d_really_is_positive/negative() when looking at its own dentries rather than d_is_positive/negative() and should use d_inode() to get at the inode. Anyone looking at someone else's dentries (this includes pathwalk) should use d_is_xxx() and d_backing_inode(). Signed-off-by: David Howells Signed-off-by: Al Viro --- Reading git-diff-tree failed