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authorPranith Kumar K <pkarampu@redhat.com>2013-12-11 09:33:53 +0530
committerAnand Avati <avati@redhat.com>2014-01-19 23:05:15 -0800
commit8d55c25f158921b508bff0e7f25158991913f922 (patch)
tree258500ed1f6b15d6f2f6848a5cbd883b8dc40ea2 /api/src/glfs-fops.c
parentc2b09dc87e0763dfdff1e93a1dc6cc4c05f091bf (diff)
syncop: Change return value of syncop
Problem: We found a day-1 bug when syncop_xxx() infra is used inside a synctask with compilation optimization (CFLAGS -O2). Detailed explanation of the Root cause: We found the bug in 'gf_defrag_migrate_data' in rebalance operation: Lets look at interesting parts of the function: int gf_defrag_migrate_data (xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc, dict_t *migrate_data) { ..... code section - [ Loop ] while ((ret = syncop_readdirp (this, fd, 131072, offset, NULL, &entries)) != 0) { ..... code section - [ ERRNO-1 ] (errno of readdirp is stored in readdir_operrno by a thread) /* Need to keep track of ENOENT errno, that means, there is no need to send more readdirp() */ readdir_operrno = errno; ..... code section - [ SYNCOP-1 ] (syncop_getxattr is called by a thread) ret = syncop_getxattr (this, &entry_loc, &dict, GF_XATTR_LINKINFO_KEY); code section - [ ERRNO-2] (checking for failures of syncop_getxattr(). This may not always be executed in same thread which executed [SYNCOP-1]) if (ret < 0) { if (errno != ENODATA) { loglevel = GF_LOG_ERROR; defrag->total_failures += 1; ..... } the function above could be executed by thread(t1) till [SYNCOP-1] and code from [ERRNO-2] can be executed by a different thread(t2) because of the way syncop-infra schedules the tasks. when the code is compiled with -O2 optimization this is the assembly code that is generated: [ERRNO-1] 1165 readdir_operrno = errno; <<---- errno gets expanded as *(__errno_location()) 0x00007fd149d48b60 <+496>: callq 0x7fd149d410c0 <address@hidden> 0x00007fd149d48b72 <+514>: mov %rax,0x50(%rsp) <<------ Address returned by __errno_location() is stored in a special location in stack for later use. 0x00007fd149d48b77 <+519>: mov (%rax),%eax 0x00007fd149d48b79 <+521>: mov %eax,0x78(%rsp) .... [ERRNO-2] 1281 if (errno != ENODATA) { 0x00007fd149d492ae <+2366>: mov 0x50(%rsp),%rax <<----- Because it already stored the address returned by __errno_location(), it just dereferences the address to get the errno value. BUT THIS CODE NEED NOT BE EXECUTED BY SAME THREAD!!! 0x00007fd149d492b3 <+2371>: mov $0x9,%ebp 0x00007fd149d492b8 <+2376>: mov (%rax),%edi 0x00007fd149d492ba <+2378>: cmp $0x3d,%edi The problem is that __errno_location() value of t1 and t2 are different. So [ERRNO-2] ends up reading errno of t1 instead of errno of t2 even though t2 is executing [ERRNO-2] code section. When code is compiled without any optimization for [ERRNO-2]: 1281 if (errno != ENODATA) { 0x00007fd58e7a326f <+2237>: callq 0x7fd58e797300 <address@hidden><<--- As it is calling __errno_location() again it gets the location from t2 so it works as intended. 0x00007fd58e7a3274 <+2242>: mov (%rax),%eax 0x00007fd58e7a3276 <+2244>: cmp $0x3d,%eax 0x00007fd58e7a3279 <+2247>: je 0x7fd58e7a32a1 <gf_defrag_migrate_data+2287> Fix: Make syncop_xxx() return (-errno) value as the return value in case of errors and all the functions which make syncop_xxx() will need to use (-ret) to figure out the reason for failure in case of syncop_xxx() failures. Change-Id: I314d20dabe55d3e62ff66f3b4adb1cac2eaebb57 BUG: 1040356 Signed-off-by: Pranith Kumar K <pkarampu@redhat.com> Reviewed-on: http://review.gluster.org/6475 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Anand Avati <avati@redhat.com>
Diffstat (limited to 'api/src/glfs-fops.c')
-rw-r--r--api/src/glfs-fops.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/api/src/glfs-fops.c b/api/src/glfs-fops.c
index 5ea54567d74..67d5616fe21 100644
--- a/api/src/glfs-fops.c
+++ b/api/src/glfs-fops.c
@@ -124,6 +124,7 @@ retry:
}
ret = syncop_open (subvol, &loc, flags, glfd->fd);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
out:
@@ -169,6 +170,7 @@ glfs_close (struct glfs_fd *glfd)
}
ret = syncop_flush (subvol, fd);
+ DECODE_SYNCOP_ERR (ret);
out:
fs = glfd->fs;
glfs_fd_destroy (glfd);
@@ -273,6 +275,7 @@ glfs_fstat (struct glfs_fd *glfd, struct stat *stat)
}
ret = syncop_fstat (subvol, fd, &iatt);
+ DECODE_SYNCOP_ERR (ret);
if (ret == 0 && stat)
glfs_iatt_to_stat (glfd->fs, &iatt, stat);
@@ -392,9 +395,11 @@ retry:
if (ret == 0) {
ret = syncop_open (subvol, &loc, flags, glfd->fd);
+ DECODE_SYNCOP_ERR (ret);
} else {
ret = syncop_create (subvol, &loc, flags, mode, glfd->fd,
xattr_req, &iatt);
+ DECODE_SYNCOP_ERR (ret);
}
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -484,6 +489,7 @@ glfs_preadv (struct glfs_fd *glfd, const struct iovec *iovec, int iovcnt,
size = iov_length (iovec, iovcnt);
ret = syncop_readv (subvol, fd, size, offset, 0, &iov, &cnt, &iobref);
+ DECODE_SYNCOP_ERR (ret);
if (ret <= 0)
goto out;
@@ -833,6 +839,7 @@ glfs_pwritev (struct glfs_fd *glfd, const struct iovec *iovec, int iovcnt,
iov.iov_len = size;
ret = syncop_writev (subvol, fd, &iov, 1, offset, iobref, flags);
+ DECODE_SYNCOP_ERR (ret);
iobuf_unref (iobuf);
iobref_unref (iobref);
@@ -1005,6 +1012,7 @@ glfs_fsync (struct glfs_fd *glfd)
}
ret = syncop_fsync (subvol, fd, 0);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref (fd);
@@ -1079,6 +1087,7 @@ glfs_fdatasync (struct glfs_fd *glfd)
}
ret = syncop_fsync (subvol, fd, 1);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref (fd);
@@ -1120,6 +1129,7 @@ glfs_ftruncate (struct glfs_fd *glfd, off_t offset)
}
ret = syncop_ftruncate (subvol, fd, offset);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref (fd);
@@ -1188,6 +1198,7 @@ retry:
goto out;
ret = syncop_access (subvol, &loc, mode);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
out:
@@ -1263,6 +1274,7 @@ retry:
}
ret = syncop_symlink (subvol, &loc, data, xattr_req, &iatt);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -1313,6 +1325,7 @@ retry:
}
ret = syncop_readlink (subvol, &loc, &linkval, bufsiz);
+ DECODE_SYNCOP_ERR (ret);
if (ret > 0) {
memcpy (buf, linkval, ret);
GF_FREE (linkval);
@@ -1392,6 +1405,7 @@ retry:
}
ret = syncop_mknod (subvol, &loc, mode, dev, xattr_req, &iatt);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -1473,6 +1487,7 @@ retry:
}
ret = syncop_mkdir (subvol, &loc, mode, xattr_req, &iatt);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -1522,6 +1537,7 @@ retry:
}
ret = syncop_unlink (subvol, &loc);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -1568,6 +1584,7 @@ retry:
}
ret = syncop_rmdir (subvol, &loc, 0);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -1631,6 +1648,7 @@ retrynew:
/* TODO: check if new or old is a prefix of the other, and fail EINVAL */
ret = syncop_rename (subvol, &oldloc, &newloc);
+ DECODE_SYNCOP_ERR (ret);
if (ret == -1 && errno == ESTALE) {
if (reval < DEFAULT_REVAL_COUNT) {
@@ -1708,6 +1726,7 @@ retrynew:
newloc.inode = inode_ref (oldloc.inode);
ret = syncop_link (subvol, &oldloc, &newloc);
+ DECODE_SYNCOP_ERR (ret);
if (ret == -1 && errno == ESTALE) {
loc_wipe (&oldloc);
@@ -1782,6 +1801,7 @@ retry:
}
ret = syncop_opendir (subvol, &loc, glfd->fd);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
out:
@@ -1972,6 +1992,7 @@ glfd_entry_refresh (struct glfs_fd *glfd, int plus)
else
ret = syncop_readdir (subvol, fd, 131072, glfd->offset,
&entries);
+ DECODE_SYNCOP_ERR (ret);
if (ret >= 0) {
if (plus)
gf_link_inodes_from_dirent (THIS, fd->inode, &entries);
@@ -2150,6 +2171,7 @@ retry:
goto out;
ret = syncop_statfs (subvol, &loc, buf);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
out:
@@ -2191,6 +2213,7 @@ retry:
goto out;
ret = syncop_setattr (subvol, &loc, iatt, valid, 0, 0);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
out:
@@ -2226,6 +2249,7 @@ glfs_fsetattr (struct glfs_fd *glfd, struct iatt *iatt, int valid)
}
ret = syncop_fsetattr (subvol, fd, iatt, valid, 0, 0);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref (fd);
@@ -2442,6 +2466,7 @@ retry:
goto out;
ret = syncop_getxattr (subvol, &loc, &xattr, name);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -2500,6 +2525,7 @@ glfs_fgetxattr (struct glfs_fd *glfd, const char *name, void *value,
}
ret = syncop_fgetxattr (subvol, fd, &xattr, name);
+ DECODE_SYNCOP_ERR (ret);
if (ret)
goto out;
@@ -2570,6 +2596,7 @@ retry:
goto out;
ret = syncop_getxattr (subvol, &loc, &xattr, NULL);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -2625,6 +2652,7 @@ glfs_flistxattr (struct glfs_fd *glfd, void *value, size_t size)
}
ret = syncop_fgetxattr (subvol, fd, &xattr, NULL);
+ DECODE_SYNCOP_ERR (ret);
if (ret)
goto out;
@@ -2697,6 +2725,7 @@ retry:
}
ret = syncop_setxattr (subvol, &loc, xattr, flags);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -2760,6 +2789,7 @@ glfs_fsetxattr (struct glfs_fd *glfd, const char *name, const void *value,
}
ret = syncop_fsetxattr (subvol, fd, xattr, flags);
+ DECODE_SYNCOP_ERR (ret);
out:
if (xattr)
dict_unref (xattr);
@@ -2803,6 +2833,7 @@ retry:
goto out;
ret = syncop_removexattr (subvol, &loc, name);
+ DECODE_SYNCOP_ERR (ret);
ESTALE_RETRY (ret, errno, reval, &loc, retry);
@@ -2853,6 +2884,7 @@ glfs_fremovexattr (struct glfs_fd *glfd, const char *name)
}
ret = syncop_fremovexattr (subvol, fd, name);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref (fd);
@@ -2887,6 +2919,7 @@ glfs_fallocate (struct glfs_fd *glfd, int keep_size, off_t offset, size_t len)
}
ret = syncop_fallocate (subvol, fd, keep_size, offset, len);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref(fd);
@@ -2921,6 +2954,7 @@ glfs_discard (struct glfs_fd *glfd, off_t offset, size_t len)
}
ret = syncop_discard (subvol, fd, offset, len);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref(fd);
@@ -2952,6 +2986,7 @@ glfs_zerofill (struct glfs_fd *glfd, off_t offset, off_t len)
}
ret = syncop_zerofill (subvol, fd, offset, len);
+ DECODE_SYNCOP_ERR (ret);
out:
if (fd)
fd_unref(fd);
@@ -3200,6 +3235,7 @@ glfs_posix_lock (struct glfs_fd *glfd, int cmd, struct flock *flock)
gf_flock_from_flock (&gf_flock, flock);
gf_flock_from_flock (&saved_flock, flock);
ret = syncop_lk (subvol, fd, cmd, &gf_flock);
+ DECODE_SYNCOP_ERR (ret);
gf_flock_to_flock (&gf_flock, flock);
if (ret == 0 && (cmd == F_SETLK || cmd == F_SETLKW))