[fuse-devel] read syscall --> No such file or directory at Fuse kernel level ???

[François T. <thi...@gm...>]

Dear miklos,

I can't figure out the meaning of such an error.
We assume that files 'file' and 'file.tmp' contain some data. We then use
the following syscall sequence on our filesystem (*Fuse is single thread*) :

<thread_reader> open 'file'
<thread_writer> rename 'file.tmp' --> 'file'
<thread_read> read from opened 'file'

unique: 32525, opcode: READ (15), nodeid: 662, insize: 80
   unique: 32525, error: -2 (No such file or directory), outsize: 16

this READ syscall never reach our filesystem, it seems that Fuse kernel part
reply directly (even in direct-io mode)

So my question is : how is it possible to successfully open a file and then
being unable to find it ?

Please note that our filesystem take care of such situation : the unlinked
file 'file' has nlink=0 and its inode will be deleted as soon as 'file' is
closed by the reader.



We use a vanilla kernel 2.6.28.2 along with fuse-2.8.0-pre2 (the same occurs
with fuse-2.7.4). Fuse launch parameters are described below :

VFS 0<30330 1242478095.917> -   :       visagefs.fsargv.argv[2] = -f
[visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.917> -   :       visagefs.fsargv.argv[3] =
-ohard_remove [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.917> -   :       visagefs.fsargv.argv[4] =
-oallow_other [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.917> -   :       visagefs.fsargv.argv[5] =
-ofsname=visagefs [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[6] = -ouse_ino
[visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[7] =
-oentry_timeout=1.0 [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[8] =
-oattr_timeout=1.0 [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[9] =
-onegative_timeout=1.0 [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[10] =
-oauto_cache [visagefs_main-visagefs_main.c:5552]
VFS 0<30330 1242478095.918> -   :       visagefs.fsargv.argv[11] =
-obig_writes [visagefs_main-visagefs_main.c:5552]

Please not that the same error occurs with Fuse being launched in a single
thread way.

Thanks.

François.

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