Re: [Libguestfs] [PATCH] file: Normalize errno value for ENODEV

Fix issues Eric found in the original patch: https://www.redhat.com/archives/libguestfs/2018-July/msg00072.html - When handling ENODEV, the caller is expecting ENOTSUPP to trigger fallback. - ENODEV should be ignored in file_trim. Tested only on Fedora 28. --- plugins/file/file.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/plugins/file/file.c b/plugins/file/file.c index a7c07fb..4210adb 100644 --- a/plugins/file/file.c +++ b/plugins/file/file.c @@ -50,6 +50,21 @@ static char *filename = NULL; +#if defined(FALLOC_FL_PUNCH_HOLE) || defined(FALLOC_FL_ZERO_RANGE) +static int +do_fallocate(int fd, int mode, off_t offset, off_t len) +{ + int r = -1; + r = fallocate (fd, mode, offset, len); + /* kernel 3.10 fails with ENODEV for block device. Kernel >= 4.9 fails + with EOPNOTSUPP in this case. Normlize errno to simplify callers. */ + if (r == -1 && errno == ENODEV) { + errno = EOPNOTSUPP; + } + return r; +} +#endif + static void file_unload (void) { @@ -241,9 +256,9 @@ file_zero (void *handle, uint32_t count, uint64_t offset, int may_trim) #ifdef FALLOC_FL_PUNCH_HOLE if (may_trim) { - r = fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, - offset, count); - if (r == -1 && errno != EOPNOTSUPP && errno != ENODEV) { + r = do_fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + offset, count); + if (r == -1 && errno != EOPNOTSUPP) { nbdkit_error ("zero: %m"); } /* PUNCH_HOLE is older; if it is not supported, it is likely that @@ -253,8 +268,8 @@ file_zero (void *handle, uint32_t count, uint64_t offset, int may_trim) #endif #ifdef FALLOC_FL_ZERO_RANGE - r = fallocate (h->fd, FALLOC_FL_ZERO_RANGE, offset, count); - if (r == -1 && errno != EOPNOTSUPP && errno != ENODEV) { + r = do_fallocate (h->fd, FALLOC_FL_ZERO_RANGE, offset, count); + if (r == -1 && errno != EOPNOTSUPP) { nbdkit_error ("zero: %m"); } #else @@ -288,11 +303,11 @@ file_trim (void *handle, uint32_t count, uint64_t offset) struct handle *h = handle; /* Trim is advisory; we don't care if it fails for anything other - * than EIO, EPERM, or ENODEV (kernel 3.10) */ - r = fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, - offset, count); + * than EIO or EPERM. */ + r = do_fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + offset, count); if (r < 0) { - if (errno != EPERM && errno != EIO && errno != ENODEV) { + if (errno != EPERM && errno != EIO) { nbdkit_debug ("ignoring failed fallocate during trim: %m"); r = 0; }