Reading large collections of blocks, as gfs2_rgrp_read may do with large rgrps and small block sizes, can cause preadv() to fail with EINVAL in breadm(). This patch splits large reads into IOV_MAX chunks to avoid reads failing in that way. It also includes a test to exercise these changes.
Signed-off-by: Andrew Price <[email protected]> --- gfs2/libgfs2/buf.c | 57 ++++++++++++++++++++++++++++++++---------------------- tests/mkfs.at | 4 ++++ 2 files changed, 38 insertions(+), 23 deletions(-) diff --git a/gfs2/libgfs2/buf.c b/gfs2/libgfs2/buf.c index 6fcdd17..92cd393 100644 --- a/gfs2/libgfs2/buf.c +++ b/gfs2/libgfs2/buf.c @@ -15,6 +15,14 @@ #include "libgfs2.h" +#ifndef IOV_MAX + #ifdef UIO_MAXIOV + #define IOV_MAX UIO_MAXIOV + #else + #define IOV_MAX (1024) + #endif +#endif + struct gfs2_buffer_head *bget(struct gfs2_sbd *sdp, uint64_t num) { struct gfs2_buffer_head *bh; @@ -34,31 +42,34 @@ struct gfs2_buffer_head *bget(struct gfs2_sbd *sdp, uint64_t num) int __breadm(struct gfs2_sbd *sdp, struct gfs2_buffer_head **bhs, size_t n, uint64_t block, int line, const char *caller) { - struct iovec *iov = alloca(n * sizeof(struct iovec)); + size_t v = (n < IOV_MAX) ? n : IOV_MAX; + struct iovec *iov = alloca(v * sizeof(struct iovec)); struct iovec *iovbase = iov; - uint64_t b = block; - size_t size = 0; - size_t i; - int ret; - - for (i = 0; i < n; i++) { - bhs[i] = bget(sdp, b++); - if (bhs[i] == NULL) - return -1; - *iov++ = bhs[i]->iov; - size += bhs[i]->iov.iov_len; + size_t i = 0; + + while (i < n) { + int j; + ssize_t ret; + ssize_t size = 0; + + for (j = 0; (i + j < n) && (j < IOV_MAX); j++) { + bhs[i + j] = bget(sdp, block + i + j); + if (bhs[i + j] == NULL) + return -1; + iov[j] = bhs[i + j]->iov; + size += bhs[i + j]->iov.iov_len; + } + + ret = preadv(sdp->device_fd, iovbase, j, (block + i) * sdp->bsize); + if (ret != size) { + fprintf(stderr, "bad read: %s from %s:%d: block %llu (0x%llx) " + "count: %d size: %zd ret: %zd\n", strerror(errno), + caller, line, (unsigned long long)block, + (unsigned long long)block, j, size, ret); + exit(-1); + } + i += j; } - - ret = preadv(sdp->device_fd, iovbase, n, block * sdp->bsize); - - if (ret != size) { - fprintf(stderr, "bad read: %s from %s:%d: block " - "%llu (0x%llx)\n", strerror(errno), - caller, line, (unsigned long long)block, - (unsigned long long)block); - exit(-1); - } - return 0; } diff --git a/tests/mkfs.at b/tests/mkfs.at index 2616109..ff99bb1 100644 --- a/tests/mkfs.at +++ b/tests/mkfs.at @@ -54,6 +54,10 @@ AT_SETUP([Min. resource group size]) GFS_FSCK_CHECK([$GFS_MKFS -p lock_nolock -r 32 $GFS_TGT]) AT_CLEANUP +AT_SETUP([Max. resource group size, min. block size]) +GFS_FSCK_CHECK([$GFS_MKFS -p lock_nolock -r 2048 -b 512 $GFS_TGT]) +AT_CLEANUP + AT_SETUP([Max. journal size]) GFS_FSCK_CHECK([$GFS_MKFS -p lock_nolock -J 1024 $GFS_TGT]) AT_CLEANUP -- 1.8.5.3
