Renamed tailp -> ptail

This is mainly just to match pcache.

Which is where I would put ptail if these two didn't have annoyingly
different flush semantics.

lfs.c

@@ -701,24 +701,24 @@ static int lfsr_bd_set(lfs_t *lfs, lfs_block_t block, lfs_size_t off,
 
 
 
-// lfsr_tailp_t stuff
+// lfsr_ptail_t stuff
 //
-// tailp tracks the most recent trunk's parity so we can parity-check
+// ptail tracks the most recent trunk's parity so we can parity-check
 // if it hasn't been written to disk yet
 
 #ifdef LFS_CKPARITY
-#define LFSR_TAILP_PARITY 0x80000000
+#define LFSR_PTAIL_PARITY 0x80000000
 #endif
 
 #ifdef LFS_CKPARITY
-static inline bool lfsr_tailp_parity(const lfsr_tailp_t *tailp) {
+static inline bool lfsr_ptail_parity(const lfsr_ptail_t *ptail) {
-    return tailp->off & LFSR_TAILP_PARITY;
+    return ptail->off & LFSR_PTAIL_PARITY;
 }
 #endif
 
 #ifdef LFS_CKPARITY
-static inline lfs_size_t lfsr_tailp_off(const lfsr_tailp_t *tailp) {
+static inline lfs_size_t lfsr_ptail_off(const lfsr_ptail_t *ptail) {
-    return tailp->off & ~LFSR_TAILP_PARITY;
+    return ptail->off & ~LFSR_PTAIL_PARITY;
 }
 #endif
 
@@ -1526,14 +1526,14 @@ static lfs_ssize_t lfsr_bd_readtag(lfs_t *lfs,
         //
         // unless we're in the middle of building a commit, where things get
         // tricky... to avoid problems with not-yet-written parity bits
-        // tailp tracks the most recent trunk's parity
+        // ptail tracks the most recent trunk's parity
         //
 
-        // parity in in tailp?
+        // parity in in ptail?
         bool parity;
-        if (block == lfs->tailp.block
+        if (block == lfs->ptail.block
-                && off+d_ == lfsr_tailp_off(&lfs->tailp)) {
+                && off+d_ == lfsr_ptail_off(&lfs->ptail)) {
-            parity = lfsr_tailp_parity(&lfs->tailp);
+            parity = lfsr_ptail_parity(&lfs->ptail);
 
         // parity on disk?
         } else {
@@ -3440,8 +3440,8 @@ static int lfsr_rbyd_appendtag(lfs_t *lfs, lfsr_rbyd_t *rbyd,
 
     #ifdef LFS_CKPARITY
     // keep track of most recent parity
-    lfs->tailp.block = rbyd->blocks[0];
+    lfs->ptail.block = rbyd->blocks[0];
-    lfs->tailp.off
+    lfs->ptail.off
             = ((lfs_size_t)(
                     lfs_parity(rbyd->cksum) ^ lfsr_rbyd_isperturb(rbyd)
                 ) << (8*sizeof(lfs_size_t)-1))
@@ -3648,8 +3648,8 @@ static int lfsr_rbyd_appendrattr_(lfs_t *lfs, lfsr_rbyd_t *rbyd,
 
     #ifdef LFS_CKPARITY
     // keep track of most recent parity
-    lfs->tailp.block = rbyd->blocks[0];
+    lfs->ptail.block = rbyd->blocks[0];
-    lfs->tailp.off
+    lfs->ptail.off
             = ((lfs_size_t)(
                     lfs_parity(rbyd->cksum) ^ lfsr_rbyd_isperturb(rbyd)
                 ) << (8*sizeof(lfs_size_t)-1))
@@ -13053,9 +13053,9 @@ static int lfs_init(lfs_t *lfs, uint32_t flags,
     }
 
     #ifdef LFS_CKPARITY
-    // setup tailp, nothing should actually check off=0
+    // setup ptail, nothing should actually check off=0
-    lfs->tailp.block = 0;
+    lfs->ptail.block = 0;
-    lfs->tailp.off = 0;
+    lfs->ptail.off = 0;
     #endif
 
     // setup lookahead buffer, note mount finishes initializing this after

lfs.h

@@ -798,11 +798,11 @@ typedef struct lfsr_grm {
 } lfsr_grm_t;
 
 #ifdef LFS_CKPARITY
-typedef struct lfsr_tailp {
+typedef struct lfsr_ptail {
     lfs_block_t block;
     // sign(off) => tail parity
     lfs_size_t off;
-} lfsr_tailp_t;
+} lfsr_ptail_t;
 #endif
 
 // The littlefs filesystem type
@@ -837,7 +837,7 @@ typedef struct lfs {
     } pcache;
 
     #ifdef LFS_CKPARITY
-    lfsr_tailp_t tailp;
+    lfsr_ptail_t ptail;
     #endif
 
     struct lfs_lookahead {