X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=fusefile.c;h=eeb0e72789f1e322b52419b2fcd04ebf3b995fc1;hb=e46d32a7a6068d96db47e39c959105ee2acda8ba;hp=99424c5fd8ea7f8b1247d404da41cd8be7f06280;hpb=6637283f63bfa51cbf0ae0746a6702cb2b6014e7;p=rrq%2Ffusefile.git

diff --git a/fusefile.c b/fusefile.c
index 99424c5..eeb0e72 100644
--- a/fusefile.c
+++ b/fusefile.c
@@ -35,8 +35,8 @@
 #include <errno.h>
 
 struct Region {
-    off_t pos;
-    size_t size;
+    off_t beg;
+    off_t end;
 };
 
 struct Source {
@@ -45,6 +45,7 @@ struct Source {
     ssize_t to;
     ssize_t start; // starting position in concatenated file
     int fd;
+    int dirty;
 };
 
 static struct {
@@ -69,18 +70,20 @@ static struct {
     size_t limit;
 } overlay;
 
-#define FRAG(m) (overlay.table+m)
-#define BEG(m) (FRAG(m)->pos)
-#define END(m) (FRAG(m)->pos + FRAG(m)->size)
+static void usage();
 
+/**
+ * Find the nearest overlay.table region below pos. Returns the index,
+ * or -1 if there is none, i.e. pos < overlay.table[0].
+ */
 static ssize_t overlay_prior_fragment(off_t pos) {
     size_t lo = 0, hi = overlay.count;
     while ( lo < hi ) {
 	size_t m = ( lo + hi ) / 2;
 	if ( m == lo ) {
-	    return BEG( m ) < pos? m : -1;
+	    return overlay.table[m].beg <= pos? m : -1;
 	}
-	if ( BEG( m ) <= pos ) {
+	if ( overlay.table[m].beg <= pos ) {
 	    lo = m;
 	} else {
 	    hi = m;
@@ -89,6 +92,11 @@ static ssize_t overlay_prior_fragment(off_t pos) {
     return -1;
 }
 
+/**
+ * Save the entry count for overlay.table as 64-bit integer
+ * immediately following the overlay content at the index
+ * corresponding to the fused file size.
+ */
 static void overlay_save_count() {
     lseek( overlay.source.fd, overlay.source.to, SEEK_SET );
     size_t size = sizeof( overlay.count );
@@ -102,10 +110,19 @@ static void overlay_save_count() {
 	size -= n;
 	p += n;
     }
+    if ( overlay.source.dirty++ > 1000 ) {
+	fsync( overlay.source.fd );
+	overlay.source.dirty = 0;
+    }
 }
 
+/**
+ * Update the on-disk cache of overlay.table between the given
+ * indexes. The table is laid out immediately following the table
+ * count with each region saved as two 64-bit unsigned integers.
+ */
 static void overlay_save_table(size_t lo,size_t hi) {
-    char *p = (char *) FRAG(lo);
+    char *p = (char *) &overlay.table[ lo ];
     size_t pos =  overlay.source.to + sizeof( overlay.count ) +
 	lo * sizeof( struct Region );
     size_t size = ( hi - lo ) * sizeof( struct Region );
@@ -122,10 +139,19 @@ static void overlay_save_table(size_t lo,size_t hi) {
 	size -= n;
 	p += n;
     }
+    if ( overlay.source.dirty++ > 1000 ) {
+	fsync( overlay.source.fd );
+	overlay.source.dirty = 0;
+    }
 }
 
-static void overlay_insert(size_t p,off_t pos,size_t size) {
+/**
+ * Insert a new region at index p, with previous portion [p,count]
+ * moved up to make space.
+ */
+static void overlay_insert(size_t p,off_t beg,off_t end) {
     size_t bytes;
+    // Grow the table if needed
     if ( overlay.count >= overlay.limit ) {
 	overlay.limit = overlay.count + 10;
 	bytes = overlay.limit * sizeof( struct Region );
@@ -134,44 +160,120 @@ static void overlay_insert(size_t p,off_t pos,size_t size) {
     }
     bytes = ( overlay.count++ - p ) * sizeof( struct Region );
     if ( bytes ) {
-	memmove( FRAG( p+1 ), FRAG( p ), bytes );
+	memmove( (char*) &overlay.table[ p+1 ],
+		 (char*) &overlay.table[ p ],
+		 bytes );
     }
-    FRAG( p )->pos = pos;
-    FRAG( p )->size = size;
+    overlay.table[ p ].beg = beg;
+    overlay.table[ p ].end = end;
     overlay_save_count();
 }
 
+/**
+ * Delete the region entry at p by moving the portion [p+1,count]
+ * down.
+ */
 static void overlay_delete(size_t p) {
-    if ( p < --overlay.count ) {
-	size_t size = ( overlay.count - p ) * sizeof( struct Region );
-	memmove( FRAG(p), FRAG(p+1), size );
+    size_t bytes = ( --overlay.count - p ) * sizeof( struct Region );
+    if ( bytes ) {
+	memmove( (char*) &overlay.table[ p ],
+		 (char*) &overlay.table[ p+1 ],
+		 bytes );
     }
-    overlay_save_count();
 }
 
-static void overlay_mark(off_t pos,size_t size) {
-    ssize_t p = overlay_prior_fragment( pos );
-    if ( p >= 0 && pos <= END(p) ) {
-	// Merge new marks with fragment p
-	FRAG(p)->size = pos + size - BEG(p);
-	if ( p+1 < overlay.count && BEG(p+1) <= END(p) ) {
-	    FRAG(p)->size = END(p+1) - BEG(p);
-	    overlay_delete( p+1 );
-	    overlay_save_table( p, overlay.count );
-	} else {
-	    overlay_save_table( p, p+1 );
+/**
+ * Mark the given region as updated, i.e. written to the overlay. The
+ * mark region may attach to prior marked regions or be a new,
+ * separate region. If attaching, it causes the prior regions to
+ * expand and the table adjusted by deleting any regions that become
+ * fully contained in other regions.
+ */
+static void overlay_mark(off_t beg,off_t end) {
+#if DEBUG
+    fprintf( stderr, "overlay_mark( %ld, %ld )\n", beg, end );
+#endif
+    int deleted = 0;
+    ssize_t q;
+    ssize_t p = overlay_prior_fragment( beg );
+    // p is the nearest region below or at beg (or -1)
+    if ( p >= 0 && beg <= overlay.table[p].end ) {
+	// p overlaps mark region
+	if ( end <= overlay.table[p].end ) {
+	    // region p covers mark region already
+#if DEBUG
+	    fprintf( stderr, "overlay covering ( %ld %ld )\n",
+		     overlay.table[p].beg, overlay.table[p].end );
+#endif
+	    return;
+	}
+	// the new mark region extends region p
+	overlay.table[p].end = end;
+	q = p+1;
+	while ( q < overlay.count &&
+		overlay.table[q].beg <= overlay.table[p].end ) {
+	    // Extended region merges with subsequent region
+	    if ( overlay.table[p].end < overlay.table[q].end ) {
+		overlay.table[p].end = overlay.table[q].end;
+	    }
+	    overlay_delete( q );
+	    deleted++;
+	}
+	if ( deleted ) {
+	    overlay_save_count();
+	    q = overlay.count;
 	}
+	overlay_save_table( p, q );
+#if DEBUG
+	fprintf( stderr, "overlay expand ( %ld %ld ) deleted %d\n",
+		 overlay.table[p].beg, overlay.table[p].end, deleted );
+#endif
 	return;
     }
-    p++; // index of subsequent fragment
-    if ( p < overlay.count && BEG(p) < pos + size ) {
-	// Merge new marks with pragment p+1
-	FRAG(p)->size = END(p) - pos;
-	FRAG(p)->pos = pos;
-	overlay_save_table( p, p+1 );
-    } else {
-	overlay_insert( p, pos, size);
+    // The prior region p does not expand into new mark region
+    p++; // subsequent region 
+    if ( p >= overlay.count || end < overlay.table[p].beg ) {
+	// New mark region is a separate region at p
+	overlay_insert( p, beg, end );
+#if DEBUG
+	fprintf( stderr, "overlay new ( %ld %ld )\n",
+		 overlay.table[p].beg, overlay.table[p].end );
+#endif
 	overlay_save_table( p, overlay.count );
+	return;
+    }
+    // New marks start before and overlap with region p => change p
+    // and handle any subsequent regions being covered
+    overlay.table[p].beg = beg;
+    q = p+1;
+    if ( overlay.table[p].end < end ) {
+	overlay.table[p].end = end;
+	while ( q < overlay.count &&
+		overlay.table[q].beg <= overlay.table[p].end ) {
+	    if ( overlay.table[p].end < overlay.table[q].end ) {
+		overlay.table[p].end = overlay.table[q].end;
+	    }
+	    overlay_delete( q );
+	    deleted++;
+	}
+	if ( deleted ) {
+	    overlay_save_count();
+	    q = overlay.count;
+	}
+    }
+    overlay_save_table( p, q );
+#if DEBUG
+    fprintf( stderr, "overlay before ( %ld %ld ) deleted %d\n",
+	     overlay.table[p].beg, overlay.table[p].end, deleted );
+#endif
+}
+
+static void setup_overlay(char *filename) {
+    overlay.source.filename = filename;
+    overlay.source.fd = open( filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR );
+    if ( overlay.source.fd < 0 ) {
+	perror( filename );
+	usage();
     }
 }
 
@@ -188,17 +290,6 @@ static int RANGE(int s,int n ) {
     return ( s == n ) && *(range+c) == 0;
 }
 
-static void usage();
-
-static void setup_overlay(char *filename) {
-    overlay.source.filename = filename;
-    overlay.source.fd = open( filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR );
-    if ( overlay.source.fd < 0 ) {
-	perror( filename );
-	usage();
-    }
-}
-
 static int setup_sources(char **argv,int i,int n) {
     sources.array = calloc( n, sizeof( struct Source ) );
     if ( sources.array == 0 ) {
@@ -357,40 +448,34 @@ static int find_source(off_t offset) {
     return lo;
 }
 
-static int overlay_merge(char *buf,off_t off,size_t size) {
+static int overlay_merge(char *buf,off_t beg,off_t end) {
 #if DEBUG
-    fprintf( stderr, "merge %ld %ld\n", off, size );
+    fprintf( stderr, "merge %ld %ld\n", beg, end );
 #endif
-    // Find nearest overlay data before or at off
-    ssize_t p = overlay_prior_fragment( off );
+    // Find nearest overlay data before or at beg
+    ssize_t p = overlay_prior_fragment( beg );
     if ( p < 0 ) {
 	p = 0;
     }
-    for ( ; p < overlay.count && BEG(p) < off+size; p++ ) {
-	size_t delta = FRAG(p)->size;
-	if ( BEG(p) > off ) {
-	    size_t skip = BEG(p) - off;
-	    off += skip;
-	    size -= skip;
-	    buf += skip;
-	} else {
-	    delta = off - BEG(p);
+    for ( ; p < overlay.count && overlay.table[p].beg < end; p++ ) {
+	if ( overlay.table[p].end < beg ) {
+	    continue;
 	}
-	if ( delta > size ) {
-	    delta = size;
+	if ( overlay.table[p].beg > beg ) {
+	    size_t delta = overlay.table[p].beg - beg;
+	    buf += delta;
+	    beg += delta;
 	}
-	lseek( overlay.source.fd, off, SEEK_SET );
-	while ( delta > 0 ) {
-	    size_t n = read( overlay.source.fd, buf, delta );
-	    off += n;
+	size_t size = ( overlay.table[p].end <= end )?
+	    ( overlay.table[p].end - beg ) : ( end - beg ); 
+	lseek( overlay.source.fd, beg, SEEK_SET );
+	while ( size > 0 ) {
+	    size_t n = read( overlay.source.fd, buf, size );
 	    size -= n;
-	    delta -= n;
 	    buf += n;
+	    beg += n; //
 	}
     }
-#if DEBUG
-    fprintf( stderr, "merged\n" );
-#endif
     return 0;
 }
 
@@ -428,6 +513,10 @@ static int fusefile_read(const char *path, char *buf, size_t size,
 	if ( n > size ) {
 	    n = size;
 	}
+	if ( sources.array[i].dirty ) {
+	    fsync( sources.array[i].fd );
+	    sources.array[i].dirty = 0;
+	}
 #if DEBUG
 	fprintf( stderr, "  seek fd=%d to %ld\n", sources.array[i].fd, b );
 #endif
@@ -440,12 +529,6 @@ static int fusefile_read(const char *path, char *buf, size_t size,
 		 n, sources.array[i].fd );
 #endif
 	ssize_t r = read( sources.array[i].fd, buf + rr, n );
-	if ( overlay.source.filename ) {
-	    int x = overlay_merge( buf + rr, off + rr, r );
-	    if ( x ) {
-		return x;
-	    }
-	}
 #if DEBUG
 	fprintf( stderr, "  got %ld bytes\n", r );
 #endif
@@ -456,6 +539,16 @@ static int fusefile_read(const char *path, char *buf, size_t size,
 	if ( r == 0 ) {
 	    break;
 	}
+	if ( overlay.source.filename ) {
+	    if ( overlay.source.dirty ) {
+		fsync( overlay.source.fd );
+		overlay.source.dirty = 0;
+	    }
+	    int x = overlay_merge( buf + rr, off + rr, off + rr + r );
+	    if ( x ) {
+		return x;
+	    }
+	}
 	rr += r;
 	off += r;
 	size -= r;
@@ -503,9 +596,9 @@ static void overlay_load() {
 	    exit( 1 );
 	}
 #if DEBUG
-	fprintf( stderr, "overlay region: %ld %ld\n", f.pos, f.size );
+	fprintf( stderr, "overlay region: %ld %ld\n", f.beg, f.end );
 #endif
-	overlay_mark( f.pos, f.size );
+	overlay_mark( f.beg, f.end );
     }
 }
 
@@ -516,18 +609,16 @@ static int write_block(off_t off,const char *buf,size_t size) {
 #if DEBUG
     fprintf( stderr, "write_block( %ld, ?, %ld )\n", off, size );
 #endif
+    if ( overlay.source.filename ) {
+	overlay_mark( off, off + size ); // Mark region as written
+    }
     while ( size > 0 ) {
 	int index = find_source( off ); // index of source file
 	if ( index < 0 ) {
 	    return -EIO; // past EOF
 	}
-	struct Source *source;
-	if ( overlay.source.filename ) {
-	    source = &overlay.source;
-	    overlay_mark( off, size ); // Mark region as written
-	} else {
-	    source = &sources.array[ index ];
-	}
+	struct Source *source = overlay.source.filename?
+	    &overlay.source :  &sources.array[ index ];
 	off_t from = off - source->start + source->from;
 	off_t max = source->to - from;
 	if ( lseek( source->fd, from, SEEK_SET ) < 0 ) {
@@ -545,6 +636,10 @@ static int write_block(off_t off,const char *buf,size_t size) {
 	    size -= n;
 	    off += n;
 	}
+	if ( source->dirty++ >= 1000 ) {
+	    fsync( source->fd );
+	    source->dirty = 0;
+	}
     }
     return 0;
 }
@@ -608,6 +703,20 @@ static void fusefile_destroy(void *data) {
     }
 }
 
+static void fsync_all_dirty() {
+    int i = 0;
+    for ( ; i < sources.count; i++ ) {
+	if ( sources.array[i].dirty ) {
+	    fsync( sources.array[i].fd );
+	    sources.array[i].dirty = 0;
+	}
+    }
+    if ( overlay.source.filename && overlay.source.dirty ) {
+	fsync( overlay.source.fd );
+	overlay.source.dirty = 0;
+    }
+}
+
 static int fusefile_flush(const char *path, struct fuse_file_info *info) {
 #if DEBUG
     fprintf( stderr, "fusefile_flush( %s )\n", path );
@@ -615,6 +724,7 @@ static int fusefile_flush(const char *path, struct fuse_file_info *info) {
     if ( strcmp( path, "/" ) != 0 ) {
 	return -ENOENT;
     }
+    fsync_all_dirty();
     return 0;
 }
 
@@ -635,6 +745,7 @@ static int fusefile_fsync(const char *path, int x, struct fuse_file_info *fi) {
     if ( strcmp( path, "/" ) != 0 ) {
 	return -ENOENT;
     }
+    fsync_all_dirty();
     return 0;
 }