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| author | Christian Schoenebeck <qemu_oss@crudebyte.com> | 2025-03-20 13:16:20 +0100 |
|---|---|---|
| committer | Christian Schoenebeck <qemu_oss@crudebyte.com> | 2025-05-05 11:28:29 +0200 |
| commit | cdafeda35709ddf8cd982a7eb653c2a5028c8074 (patch) | |
| tree | 501595a3da3136a9ac157b58bfe3fd45dc5b1e2c | |
| parent | 610dc187e52605c8ea8d14c5e7d8e7384f8af290 (diff) | |
| download | qemu-cdafeda35709ddf8cd982a7eb653c2a5028c8074.zip qemu-cdafeda35709ddf8cd982a7eb653c2a5028c8074.tar.gz qemu-cdafeda35709ddf8cd982a7eb653c2a5028c8074.tar.bz2 | |
9pfs: fix 'total_open_fd' decrementation
According to 'man 2 close' errors returned by close() should only be used
for either diagnostic purposes or for catching data loss due to a previous
write error, as an error result of close() usually indicates a deferred
error of a previous write operation.
Therefore not decrementing 'total_open_fd' on a close() error is wrong
and would yield in a higher open file descriptor count than actually the
case, leading to 9p server reclaiming open file descriptors too soon.
Based-on: <20250312152933.383967-7-groug@kaod.org>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <E1tvEyJ-004dMa-So@kylie.crudebyte.com>
| -rw-r--r-- | hw/9pfs/9p.c | 10 | ||||
| -rw-r--r-- | hw/9pfs/codir.c | 7 | ||||
| -rw-r--r-- | hw/9pfs/cofile.c | 7 |
3 files changed, 21 insertions, 3 deletions
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index b22df3a..8b001b9 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -510,7 +510,15 @@ void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu) err = (f->fid_type == P9_FID_DIR) ? s->ops->closedir(&s->ctx, &f->fs_reclaim) : s->ops->close(&s->ctx, &f->fs_reclaim); - if (!err) { + + /* 'man 2 close' suggests to ignore close() errors except of EBADF */ + if (unlikely(err && errno == EBADF)) { + /* + * unexpected case as FIDs were picked above by having a valid + * file descriptor + */ + error_report("9pfs: v9fs_reclaim_fd() WARNING: close() failed with EBADF"); + } else { /* total_open_fd must only be mutated on main thread */ nclosed++; } diff --git a/hw/9pfs/codir.c b/hw/9pfs/codir.c index 2068a47..bce7dd9 100644 --- a/hw/9pfs/codir.c +++ b/hw/9pfs/codir.c @@ -20,6 +20,7 @@ #include "fsdev/qemu-fsdev.h" #include "qemu/thread.h" #include "qemu/main-loop.h" +#include "qemu/error-report.h" #include "coth.h" #include "9p-xattr.h" #include "9p-util.h" @@ -353,7 +354,11 @@ int coroutine_fn v9fs_co_closedir(V9fsPDU *pdu, V9fsFidOpenState *fs) err = -errno; } }); - if (!err) { + /* 'man 2 close' suggests to ignore close() errors except of EBADF */ + if (unlikely(err && errno == EBADF)) { + /* unexpected case as we should have checked for a valid file handle */ + error_report("9pfs: WARNING: v9fs_co_closedir() failed with EBADF"); + } else { total_open_fd--; } return err; diff --git a/hw/9pfs/cofile.c b/hw/9pfs/cofile.c index 71174c3..6e775c8 100644 --- a/hw/9pfs/cofile.c +++ b/hw/9pfs/cofile.c @@ -20,6 +20,7 @@ #include "fsdev/qemu-fsdev.h" #include "qemu/thread.h" #include "qemu/main-loop.h" +#include "qemu/error-report.h" #include "coth.h" int coroutine_fn v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t st_mode, @@ -197,7 +198,11 @@ int coroutine_fn v9fs_co_close(V9fsPDU *pdu, V9fsFidOpenState *fs) err = -errno; } }); - if (!err) { + /* 'man 2 close' suggests to ignore close() errors except of EBADF */ + if (unlikely(err && errno == EBADF)) { + /* unexpected case as we should have checked for a valid file handle */ + error_report("9pfs: WARNING: v9fs_co_close() failed with EBADF"); + } else { total_open_fd--; } return err; |