fallocate: fix --dig-holes at end of files

I discovered that making a file sparse with "fallocate -d filename"
fails on the last block of a file, because - usually being partial -
the system call only zeroes that part instead of deallocating the
block. See man fallocate(2) - section "Deallocating file space".

The expected call is punching the whole block beyond eof, which
doesn't change the file length because of flag FALLOC_FL_KEEP_SIZE.

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/fallocate.c b/sys-utils/fallocate.c
index 014b94624760e4ea3ab4fc7243bd9cb986e4d2d1..ba97092fcf903a1f7b2265d55a2d4b4d7626e40a 100644 (file)
--- a/sys-utils/fallocate.c
+++ b/sys-utils/fallocate.c
@@ -264,8 +264,11 @@ static void dig_holes(int fd, off_t file_off, off_t len)
                        off += rsz;
                }
                if (hole_sz) {
+                       off_t alloc_sz = hole_sz;
+                       if (off >= end)
+                               alloc_sz += st.st_blksize;              /* meet block boundary */
                        xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
-                                       hole_start, hole_sz);
+                                       hole_start, alloc_sz);
                        ct += hole_sz;
                }
                file_off = off;