file hash: don't close file fd on lookup/add race

[fio.git] / filesetup.c

diff --git a/filesetup.c b/filesetup.c
index f4e1adcb01a10ae22c352cfe75a3a351305ccba1..9d3e06268fffc35786749ea0eb482d0f9bb7ce11 100644 (file)
--- a/filesetup.c
+++ b/filesetup.c
@@ -434,6 +434,12 @@ int generic_close_file(struct thread_data fio_unused *td, struct fio_file *f)
                ret = errno;
 
        f->fd = -1;
+
+       if (f->shadow_fd != -1) {
+               close(f->shadow_fd);
+               f->shadow_fd = -1;
+       }
+
        return ret;
 }
 
@@ -462,6 +468,24 @@ int file_lookup_open(struct fio_file *f, int flags)
        return from_hash;
 }
 
+static int file_close_shadow_fds(struct thread_data *td)
+{
+       struct fio_file *f;
+       int num_closed = 0;
+       unsigned int i;
+
+       for_each_file(td, f, i) {
+               if (f->shadow_fd == -1)
+                       continue;
+
+               close(f->shadow_fd);
+               f->shadow_fd = -1;
+               num_closed++;
+       }
+
+       return num_closed;
+}
+
 int generic_open_file(struct thread_data *td, struct fio_file *f)
 {
        int is_std = 0;
@@ -536,6 +560,8 @@ open_again:
                        flags &= ~FIO_O_NOATIME;
                        goto open_again;
                }
+               if (__e == EMFILE && file_close_shadow_fds(td))
+                       goto open_again;
 
                snprintf(buf, sizeof(buf) - 1, "open(%s)", f->file_name);
 
@@ -552,9 +578,22 @@ open_again:
                        int fio_unused ret;
 
                        /*
-                        * OK to ignore, we haven't done anything with it
+                        * Stash away descriptor for later close. This is to
+                        * work-around a "feature" on Linux, where a close of
+                        * an fd that has been opened for write will trigger
+                        * udev to call blkid to check partitions, fs id, etc.
+                        * That polutes the device cache, which can slow down
+                        * unbuffered accesses.
                         */
-                       ret = generic_close_file(td, f);
+                       if (f->shadow_fd == -1)
+                               f->shadow_fd = f->fd;
+                       else {
+                               /*
+                                * OK to ignore, we haven't done anything
+                                * with it
+                                */
+                               ret = generic_close_file(td, f);
+                       }
                        goto open_again;
                }
        }
@@ -1029,6 +1068,7 @@ int add_file(struct thread_data *td, const char *fname)
        }
 
        f->fd = -1;
+       f->shadow_fd = -1;
        fio_file_reset(f);
 
        if (td->files_size <= td->files_index) {