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performance/read-ahead: don't set ra_file in fd->ctx unless all memebers of ra_file is initialized

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- If ptr to ra_file is set in fd->ctx even before initializing all its
    members, A race condition may occur b/w a thread executing ra_fstat,
    ra_readv etc (where all files open on the same inode are flushed) and
    the thread doing initialization of ra_file (in ra_open_cbk or
    ra_create_cbk). Because of this race-condition, flush_region might be
    called on an uninitialized ra_file, thereby causing crash.

Signed-off-by: Raghavendra G <raghavendra@gluster.com>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 868 (crash in ra_fstat)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=868
This commit is contained in:
Raghavendra G 2010-05-04 02:29:22 +00:00 committed by Anand V. Avati
parent bb4955c4e1
commit 3954ddddfe
1 changed files with 15 additions and 5 deletions

20
xlators/performance/read-ahead/src/read-ahead.c

@ -68,8 +68,6 @@ ra_open_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
goto unwind;
}
ret = fd_ctx_set (fd, this, (uint64_t)(long)file);
/* If O_DIRECT open, we disable caching on it */
if ((fd->flags & O_DIRECT) || ((fd->flags & O_ACCMODE) == O_WRONLY))
@ -104,9 +102,16 @@ ra_open_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
file->page_count = 1;
}
ret = fd_ctx_set (fd, this, (uint64_t)(long)file);
if (ret == -1) {
ra_file_destroy (file);
op_ret = -1;
op_errno = ENOMEM;
}
unwind:
frame->local = NULL;
unwind:
STACK_UNWIND_STRICT (open, frame, op_ret, op_errno, fd);
return 0;
@ -138,8 +143,6 @@ ra_create_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
goto unwind;
}
ret = fd_ctx_set (fd, this, (uint64_t)(long)file);
/* If O_DIRECT open, we disable caching on it */
if ((fd->flags & O_DIRECT) || ((fd->flags & O_ACCMODE) == O_WRONLY))
@ -167,6 +170,13 @@ ra_create_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
file->page_size = conf->page_size;
pthread_mutex_init (&file->file_lock, NULL);
ret = fd_ctx_set (fd, this, (uint64_t)(long)file);
if (ret == -1) {
ra_file_destroy (file);
op_ret = -1;
op_errno = ENOMEM;
}
unwind:
STACK_UNWIND_STRICT (create, frame, op_ret, op_errno, fd, inode, buf,
preparent, postparent);