From 83c59b690062c633a8b7478ac7a9ac762916b049 Mon Sep 17 00:00:00 2001 From: Raghavendra G Date: Tue, 7 Nov 2017 16:09:37 +0530 Subject: mount/fuse: use fstat in getattr implementation if any opened fd is available The restriction of using fds opened by the same Pid means fds cannot be shared across threads of multithreaded application. Note that fops from kernel have different Pid for different threads. Imagine following sequence of operations: * Turn off performance.open-behind * Thread t1 opens an fd - fd1 - on file "file". Let's assume nodeid of "file" is "nodeid-file". * Thread t2 does RENAME ("newfile", "file"). Let's assume nodeid of "newfile" as "nodeid-newfile". * t2 proceeds to do fstat (fd1) The above set of operations can sometimes result in ESTALE/ENOENT errors. RENAME overwrites "file" with "newfile" changing its nodeid from "nodeid-file" to "nodeid-newfile" and post RENAME, "nodeid-file" is removed from the backend. If fstat carries nodeid-file as argument, which can happen if lookup has not refreshed the nodeid of "file" and since t2 doesn't have an fd opened, fuse_getattr_resume uses STAT which will fail as "nodeid-file" no longer exists. Since the above set of operations and sharing of fds across multiple threads are valid, this is a bug. The fix is to use any fd opened on the inode. In this specific example fuse_getattr_resume will find fd1 and winds down the call as fstat (fd1) which won't fail. Cross-checked with "Miklos Szeredi" for any security issues with this solution and he approves the solution. Thanks to "Miklos Szeredi" for all the pointers and discussions. >Change-Id: I88dd29b3607cd2594eee9d72a1637b5346c8d49c >BUG: 1510401 >Signed-off-by: Raghavendra G (cherry picked from commit 8b57378e5596f287a7b9d106dd6fb56a624b42ee) Change-Id: I88dd29b3607cd2594eee9d72a1637b5346c8d49c BUG: 1529086 Signed-off-by: Raghavendra G --- tests/bugs/replicate/bug-913051.t | 11 ----------- xlators/mount/fuse/src/fuse-bridge.c | 2 +- 2 files changed, 1 insertion(+), 12 deletions(-) diff --git a/tests/bugs/replicate/bug-913051.t b/tests/bugs/replicate/bug-913051.t index 43d1330b138..6794995e6fe 100644 --- a/tests/bugs/replicate/bug-913051.t +++ b/tests/bugs/replicate/bug-913051.t @@ -37,17 +37,6 @@ TEST fd_open $rfd "r" $M0/dir/b TEST $CLI volume start $V0 force EXPECT_WITHIN $CHILD_UP_TIMEOUT "1" afr_child_up_status $V0 0 -#check that the files are not opned on brick-0 -TEST stat $M0/dir/a -realpatha=$(gf_get_gfid_backend_file_path $B0/${V0}0 "dir/a") -EXPECT "N" gf_check_file_opened_in_brick $V0 $H0 $B0/${V0}0 "$realpatha" -EXPECT "N" gf_check_file_opened_in_brick $V0 $H0 $B0/${V0}0 $B0/${V0}0/dir/a - -TEST stat $M0/dir/b -realpathb=$(gf_get_gfid_backend_file_path $B0/${V0}0 "dir/b") -EXPECT "N" gf_check_file_opened_in_brick $V0 $H0 $B0/${V0}0 "$realpathb" -EXPECT "N" gf_check_file_opened_in_brick $V0 $H0 $B0/${V0}0 $B0/${V0}0/dir/b - #attempt self-heal so that the files are created on brick-0 TEST dd if=$M0/dir/a of=/dev/null bs=1024k diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c index 94489d5c79a..5db7f56a588 100644 --- a/xlators/mount/fuse/src/fuse-bridge.c +++ b/xlators/mount/fuse/src/fuse-bridge.c @@ -820,7 +820,7 @@ fuse_getattr_resume (fuse_state_t *state) } if (!IA_ISDIR (state->loc.inode->ia_type)) { - state->fd = fd_lookup (state->loc.inode, state->finh->pid); + state->fd = fd_lookup (state->loc.inode, 0); } if (!state->fd) { -- cgit