linux.git/fs/splice.c, branch v6.12

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

	For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner 
Signed-off-by: Al Viro

remove call_{read,write}_iter() functions

2024-04-15T20:03:25+00:00

These have no clear purpose.  This is effectively a revert of commit
bb7462b6fd64 ("vfs: use helpers for calling f_op->{read,write}_iter()").

The patch was created with the help of a coccinelle script.

Fixes: bb7462b6fd64 ("vfs: use helpers for calling f_op->{read,write}_iter()")
Reviewed-by: Christian Brauner 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro

fs: use splice_copy_file_range() inline helper

2023-12-12T15:20:02+00:00

generic_copy_file_range() is just a wrapper around splice_file_range(),
which caps the maximum copy length.

The only caller of splice_file_range(), namely __ceph_copy_file_range()
is already ready to cope with short copy.

Move the length capping into splice_file_range() and replace the exported
symbol generic_copy_file_range() with a simple inline helper.

Suggested-by: Christoph Hellwig 
Link: https://lore.kernel.org/linux-fsdevel/20231204083849.GC32438@lst.de/
Reviewed-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231212094440.250945-3-amir73il@gmail.com
Signed-off-by: Christian Brauner

splice: return type ssize_t from all helpers

2023-12-12T15:19:59+00:00

Not sure why some splice helpers return long, maybe historic reasons.
Change them all to return ssize_t to conform to the splice methods and
to the rest of the helpers.

Suggested-by: Christian Brauner 
Link: https://lore.kernel.org/r/20231208-horchen-helium-d3ec1535ede5@brauner/
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231212094440.250945-2-amir73il@gmail.com
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner

fs: move file_start_write() into direct_splice_actor()

2023-12-01T10:39:50+00:00

The callers of do_splice_direct() hold file_start_write() on the output
file.

This may cause file permission hooks to be called indirectly on an
overlayfs lower layer, which is on the same filesystem of the output
file and could lead to deadlock with fanotify permission events.

To fix this potential deadlock, move file_start_write() from the callers
into the direct_splice_actor(), so file_start_write() will not be held
while splicing from the input file.

Suggested-by: Josef Bacik 
Link: https://lore.kernel.org/r/20231128214258.GA2398475@perftesting/
Reviewed-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231130141624.3338942-3-amir73il@gmail.com
Signed-off-by: Christian Brauner

fs: fork splice_file_range() from do_splice_direct()

2023-12-01T10:39:50+00:00

In preparation of calling do_splice_direct() without file_start_write()
held, create a new helper splice_file_range(), to be called from context
of ->copy_file_range() methods instead of do_splice_direct().

Currently, the only difference is that splice_file_range() does not take
flags argument and that it asserts that file_start_write() is held, but
we factor out a common helper do_splice_direct_actor() that will be used
later.

Use the new helper from __ceph_copy_file_range(), that was incorrectly
passing to do_splice_direct() the copy flags argument as splice flags.
The value of copy flags in ceph is always 0, so it is a smenatic bug fix.

Move the declaration of both helpers to linux/splice.h.

Reviewed-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231130141624.3338942-2-amir73il@gmail.com
Acked-by: Jeff Layton 
Signed-off-by: Christian Brauner

splice: remove permission hook from iter_file_splice_write()

2023-11-24T08:22:28+00:00

All the callers of ->splice_write(), (e.g. do_splice_direct() and
do_splice()) already check rw_verify_area() for the entire range
and perform all the other checks that are in vfs_write_iter().

Instead of creating another tiny helper for special caller, just
open-code it.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara 
Reviewed-by: Josef Bacik 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231122122715.2561213-6-amir73il@gmail.com
Signed-off-by: Christian Brauner

splice: move permission hook out of splice_file_to_pipe()

2023-11-24T08:22:28+00:00

vfs_splice_read() has a permission hook inside rw_verify_area() and
it is called from splice_file_to_pipe(), which is called from
do_splice() and do_sendfile().

do_sendfile() already has a rw_verify_area() check for the entire range.
do_splice() has a rw_verify_check() for the splice to file case, not for
the splice from file case.

Add the rw_verify_area() check for splice from file case in do_splice()
and use a variant of vfs_splice_read() without rw_verify_area() check
in splice_file_to_pipe() to avoid the redundant rw_verify_area() checks.

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231122122715.2561213-5-amir73il@gmail.com
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner

splice: move permission hook out of splice_direct_to_actor()

2023-11-24T08:22:28+00:00

vfs_splice_read() has a permission hook inside rw_verify_area() and
it is called from do_splice_direct() -> splice_direct_to_actor().

The callers of do_splice_direct() (e.g. vfs_copy_file_range()) already
call rw_verify_area() for the entire range, but the other caller of
splice_direct_to_actor() (nfsd) does not.

Add the rw_verify_area() checks in nfsd_splice_read() and use a
variant of vfs_splice_read() without rw_verify_area() check in
splice_direct_to_actor() to avoid the redundant rw_verify_area() checks.

This is needed for fanotify "pre content" events.

Acked-by: Chuck Lever 
Reviewed-by: Josef Bacik 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231122122715.2561213-4-amir73il@gmail.com
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner

splice: remove permission hook from do_splice_direct()

2023-11-24T08:22:27+00:00

All callers of do_splice_direct() have a call to rw_verify_area() for
the entire range that is being copied, e.g. by vfs_copy_file_range() or
do_sendfile() before calling do_splice_direct().

The rw_verify_area() check inside do_splice_direct() is redundant and
is called after sb_start_write(), so it is not "start-write-safe".
Remove this redundant check.

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231122122715.2561213-3-amir73il@gmail.com
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner