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The checkpoint is the top priority thread which can stop all the filesystem
operations. Let's make it RT priority.
Reviewed-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Add a check for invalid data size to avoid corrupted filesystem
from being further corrupted.
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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When generic_write_checks() returns zero, it means that
iov_iter_count() is zero, and there is no work to do.
Simply return success like all other filesystems do, rather than
proceeding down the write path, which today yields an -EFAULT in
generic_perform_write() via the
(fault_in_iov_iter_readable(i, bytes) == bytes) check when bytes
== 0.
Fixes: 11a347fb6cef ("exfat: change to get file size from DataLength")
Reported-by: Noah <kernel-org-10@maxgrass.eu>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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bitmap clear loop will take long time in __exfat_free_cluster()
if data size of file/dir enty is invalid.
If cluster bit in bitmap is already clear, stop clearing bitmap go to
out of loop.
Fixes: 31023864e67a ("exfat: add fat entry operations")
Reported-by: Kun Hu <huk23@m.fudan.edu.cn>, Jiaji Qin <jjtan24@m.fudan.edu.cn>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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This commit fixes the condition for allocating cluster to parent
directory to avoid allocating new cluster to parent directory when
there are just enough empty directory entries at the end of the
parent directory.
Fixes: af02c72d0b62 ("exfat: convert exfat_find_empty_entry() to use dentry cache")
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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Some tools like systemd's jounral need to retrieve the exit and cgroup
information after a process has already been reaped. This can e.g.,
happen when retrieving a pidfd via SCM_PIDFD or SCM_PEERPIDFD.
Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-6-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Record the exit code and cgroupid in release_task() and stash in struct
pidfs_exit_info so it can be retrieved even after the task has been
reaped.
Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-5-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Introduce a private inode slab cache for pidfs. In follow-up patches
pidfs will gain the ability to provide exit information to userspace
after the task has been reaped. This means storing exit information even
after the task has already been released and struct pid's task linkage
is gone. Store that information alongside the inode.
Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-4-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Instead od adding it into __pidfd_prepare() place it where the actual
file allocation happens and update the outdated comment.
Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-3-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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We have a helper that deals with all the required logic.
Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-1-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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ext4 and ceph already have a folio to pass; f2fs needs to be properly
converted but this will do for now. This removes a reference
to page->index and page->mapping as well as removing a call to
compound_head().
Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Link: https://lore.kernel.org/r/20250304170224.523141-1-willy@infradead.org
Acked-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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vfs_mkdir() does not guarantee to leave the child dentry hashed or make
it positive on success, and in many such cases the filesystem had to use
a different dentry which it can now return.
This patch changes vfs_mkdir() to return the dentry provided by the
filesystems which is hashed and positive when provided. This reduces
the number of cases where the resulting dentry is not positive to a
handful which don't deserve extra efforts.
The only callers of vfs_mkdir() which are interested in the resulting
inode are in-kernel filesystem clients: cachefiles, nfsd, smb/server.
The only filesystems that don't reliably provide the inode are:
- kernfs, tracefs which these clients are unlikely to be interested in
- cifs in some configurations would need to do a lookup to find the
created inode, but doesn't. cifs cannot be exported via NFS, is
unlikely to be used by cachefiles, and smb/server only has a soft
requirement for the inode, so this is unlikely to be a problem in
practice.
- hostfs, nfs, cifs may need to do a lookup (rarely for NFS) and it is
possible for a race to make that lookup fail. Actual failure
is unlikely and providing callers handle negative dentries graceful
they will fail-safe.
So this patch removes the lookup code in nfsd and smb/server and adjusts
them to fail safe if a negative dentry is provided:
- cache-files already fails safe by restarting the task from the
top - it still does with this change, though it no longer calls
cachefiles_put_directory() as that will crash if the dentry is
negative.
- nfsd reports "Server-fault" which it what it used to do if the lookup
failed. This will never happen on any file-systems that it can actually
export, so this is of no consequence. I removed the fh_update()
call as that is not needed and out-of-place. A subsequent
nfsd_create_setattr() call will call fh_update() when needed.
- smb/server only wants the inode to call ksmbd_smb_inherit_owner()
which updates ->i_uid (without calling notify_change() or similar)
which can be safely skipping on cifs (I hope).
If a different dentry is returned, the first one is put. If necessary
the fact that it is new can be determined by comparing pointers. A new
dentry will certainly have a new pointer (as the old is put after the
new is obtained).
Similarly if an error is returned (via ERR_PTR()) the original dentry is
put.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-7-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
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mkdir now allows a different dentry to be returned which is sometimes
relevant for nfs.
This patch changes the nfs_rpc_ops mkdir op to return a dentry, and
passes that back to the caller.
The mkdir nfs_rpc_op will return NULL if the original dentry should be
used. This matches the mkdir inode_operation.
nfs4_do_create() is duplicated to nfs4_do_mkdir() which is changed to
handle the specifics of directories. Consequently the current special
handling for directories is removed from nfs4_do_create()
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-6-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
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fuse already uses d_splice_alias() to ensure an appropriate dentry is
found for a newly created dentry. Now that ->mkdir can return that
dentry we do so.
This requires changing create_new_entry() to return a dentry and
handling that change in all callers.
Note that when create_new_entry() is asked to create anything other than
a directory we can be sure it will NOT return an alternate dentry as
d_splice_alias() only returns an alternate dentry for directories.
So we don't need to check for that case when passing one the result.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/174112490070.33508.15852253149143067890@noble.neil.brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
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__filemap_get_folio() returns an ERR_PTR, not NULL. There are extensive
assumptions that ctl->folio is NULL, not an error pointer, so it seems
better to fix this one place rather than change all the places which
check ctl->folio.
Fixes: baff9740bc8f ("ceph: Convert ceph_readdir_cache_control to store a folio")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Link: https://lore.kernel.org/r/20250304154818.250757-1-willy@infradead.org
Cc: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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pipe_readable(), pipe_writable(), and pipe_poll() can read "pipe->head"
and "pipe->tail" outside of "pipe->mutex" critical section. When the
head and the tail are read individually in that order, there is a window
for interruption between the two reads in which both the head and the
tail can be updated by concurrent readers and writers.
One of the problematic scenarios observed with hackbench running
multiple groups on a large server on a particular pipe inode is as
follows:
pipe->head = 36
pipe->tail = 36
hackbench-118762 [057] ..... 1029.550548: pipe_write: *wakes up: pipe not full*
hackbench-118762 [057] ..... 1029.550548: pipe_write: head: 36 -> 37 [tail: 36]
hackbench-118762 [057] ..... 1029.550548: pipe_write: *wake up next reader 118740*
hackbench-118762 [057] ..... 1029.550548: pipe_write: *wake up next writer 118768*
hackbench-118768 [206] ..... 1029.55055X: pipe_write: *writer wakes up*
hackbench-118768 [206] ..... 1029.55055X: pipe_write: head = READ_ONCE(pipe->head) [37]
... CPU 206 interrupted (exact wakeup was not traced but 118768 did read head at 37 in traces)
hackbench-118740 [057] ..... 1029.550558: pipe_read: *reader wakes up: pipe is not empty*
hackbench-118740 [057] ..... 1029.550558: pipe_read: tail: 36 -> 37 [head = 37]
hackbench-118740 [057] ..... 1029.550559: pipe_read: *pipe is empty; wakeup writer 118768*
hackbench-118740 [057] ..... 1029.550559: pipe_read: *sleeps*
hackbench-118766 [185] ..... 1029.550592: pipe_write: *New writer comes in*
hackbench-118766 [185] ..... 1029.550592: pipe_write: head: 37 -> 38 [tail: 37]
hackbench-118766 [185] ..... 1029.550592: pipe_write: *wakes up reader 118766*
hackbench-118740 [185] ..... 1029.550598: pipe_read: *reader wakes up; pipe not empty*
hackbench-118740 [185] ..... 1029.550599: pipe_read: tail: 37 -> 38 [head: 38]
hackbench-118740 [185] ..... 1029.550599: pipe_read: *pipe is empty*
hackbench-118740 [185] ..... 1029.550599: pipe_read: *reader sleeps; wakeup writer 118768*
... CPU 206 switches back to writer
hackbench-118768 [206] ..... 1029.550601: pipe_write: tail = READ_ONCE(pipe->tail) [38]
hackbench-118768 [206] ..... 1029.550601: pipe_write: pipe_full()? (u32)(37 - 38) >= 16? Yes
hackbench-118768 [206] ..... 1029.550601: pipe_write: *writer goes back to sleep*
[ Tasks 118740 and 118768 can then indefinitely wait on each other. ]
The unsigned arithmetic in pipe_occupancy() wraps around when
"pipe->tail > pipe->head" leading to pipe_full() returning true despite
the pipe being empty.
The case of genuine wraparound of "pipe->head" is handled since pipe
buffer has data allowing readers to make progress until the pipe->tail
wraps too after which the reader will wakeup a sleeping writer, however,
mistaking the pipe to be full when it is in fact empty can lead to
readers and writers waiting on each other indefinitely.
This issue became more problematic and surfaced as a hang in hackbench
after the optimization in commit aaec5a95d596 ("pipe_read: don't wake up
the writer if the pipe is still full") significantly reduced the number
of spurious wakeups of writers that had previously helped mask the
issue.
To avoid missing any updates between the reads of "pipe->head" and
"pipe->write", unionize the two with a single unsigned long
"pipe->head_tail" member that can be loaded atomically.
Using "pipe->head_tail" to read the head and the tail ensures the
lockless checks do not miss any updates to the head or the tail and
since those two are only updated under "pipe->mutex", it ensures that
the head is always ahead of, or equal to the tail resulting in correct
calculations.
[ prateek: commit log, testing on x86 platforms. ]
Reported-and-debugged-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
Closes: https://lore.kernel.org/lkml/e813814e-7094-4673-bc69-731af065a0eb@amd.com/
Reported-by: Alexey Gladkov <legion@kernel.org>
Closes: https://lore.kernel.org/all/Z8Wn0nTvevLRG_4m@example.org/
Fixes: 8cefc107ca54 ("pipe: Use head and tail pointers for the ring, not cursor and length")
Tested-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Convert f2fs_find_data_page() to f2fs_find_data_folio() and add a
compatibility wrapper. Saves six hidden calls to compound_head().
This was the last caller of f2fs_get_read_data_page(), so remove
the compatibility wrapper.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use f2fs_get_read_data_folio() instead of f2fs_get_read_data_page().
Saves a hidden call to compound_head() in f2fs_put_page().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Retrieve a folio from the page cache and use it throughout.
Saves five hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Fetch a folio from the page cache and use it throughout, saving
eight hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert f2fs_get_lock_data_page() to f2fs_get_lock_data_folio() and
add a compatibility wrapper. Removes three hidden calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert f2fs_get_read_data_page() into f2fs_get_read_data_folio() and
add a compatibility wrapper. Saves seven hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Remove one call to compound_head() and a reference to page->mapping
by calling page_folio() early on.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use f2fs_grab_cache_folio() to get a folio and use it throughout,
removing seven calls to compound_head() and a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use f2fs_get_node_folio() to get a folio and use it throughout. Remove a
few calls to compound_head() and a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Change __get_node_page() to return a folio and convert back to a page in
f2fs_get_node_page() and f2fs_get_node_page_ra().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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All its callers now have access to a folio, so pass it in. Removes
an access to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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The compiler can make some optimisations if we tell it that a function
call doesn't change this memory.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Iterate over each folio in the bio instead of each page.
Follow the pattern in ext4 for handling bounce folios. Removes
a few calls to compound_head() and references to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert fio->page to a folio then use it where folio APIs exist.
Removes a reference to page->mapping and a hidden call to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Retrieve a folio from the page cache and use it throughout. Saves six
hidden calls to compound_head() and removes a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert f2fs_grab_cache_page() into f2fs_grab_cache_folio()
and add a wrapper. Removes several calls to deprecated functions.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert last_page to last_folio in f2fs_fsync_node_pages() and
use folio APIs where they exist. Saves a few hidden calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use the folio APIs where they exist. Saves several hidden calls to
compound_head(). Also removes a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use the folio APIs where they exist. Saves several hidden calls to
compound_head(). Also removes a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Its one caller now has a folio; pass it in and do page conversions where
necessary inside flush_dirty_inode(). Saves two hidden calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use the folio APIs where they exist. Saves several hidden calls to
compound_head(). Also removes a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Use the folio APIs where they exist. Saves several hidden calls to
compound_head(). Also removes a reference to page->mapping.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert f2fs_put_page() to f2fs_folio_put() and add a wrapper.
Replaces three calls to compound_head() with one.
[Jaegeuk Kim: fix missing null pointer check in f2fs_put_page]
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Convert f2fs_wait_on_page_writeback() to f2fs_folio_wait_writeback()
and add a compatibiility wrapper. Replaces five calls to
compound_head() with one.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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User data is kept in a circular buffer backed by pages allocated as
needed. Only having space for one spare is still prone to having to
resort to allocation / freeing.
In my testing this decreases page allocs by 60% during a kernel build.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250303230409.452687-3-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The check operates on the stale value of 'head' and always loops back.
Just do it unconditionally. No functional changes.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250303230409.452687-2-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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In commit ee2e3f50629f ("mount: fix mounting of detached mounts onto
targets that reside on shared mounts") I fixed a bug where propagating
the source mount tree of an anonymous mount namespace into a target
mount tree of a non-anonymous mount namespace could be used to trigger
an integer overflow in the non-anonymous mount namespace causing any new
mounts to fail.
The cause of this was that the propagation algorithm was unable to
recognize mounts from the source mount tree that were already propagated
into the target mount tree and then reappeared as propagation targets
when walking the destination propagation mount tree.
When fixing this I disabled mount propagation into anonymous mount
namespaces. Make it possible for anonymous mount namespace to receive
mount propagation events correctly. This is no also a correctness issue
now that we allow mounting detached mount trees onto detached mount
trees.
Mark the source anonymous mount namespace with MNTNS_PROPAGATING
indicating that all mounts belonging to this mount namespace are
currently in the process of being propagated and make the propagation
algorithm discard those if they appear as propagation targets.
Link: https://lore.kernel.org/r/20250225-work-mount-propagation-v1-1-e6e3724500eb@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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clang correctly notices that the 'uflags' variable initialization
only happens in some cases:
fs/namespace.c:4622:6: error: variable 'uflags' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
4622 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) uflags = AT_EMPTY_PATH;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/namespace.c:4623:48: note: uninitialized use occurs here
4623 | from_name = getname_maybe_null(from_pathname, uflags);
| ^~~~~~
fs/namespace.c:4622:2: note: remove the 'if' if its condition is always true
4622 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) uflags = AT_EMPTY_PATH;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixes: b1e9423d65e3 ("fs: support getname_maybe_null() in move_mount()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250226081201.1876195-1-arnd@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
The previous patch series only enabled the creation of detached mounts
from detached mounts that were created via open_tree(). In such cases we
know that the origin sequence number for the newly created anonymous
mount namespace will be set to the sequence number of the mount
namespace the source mount belonged to.
But fsmount() creates an anonymous mount namespace that does not have an
origin mount namespace as the anonymous mount namespace was derived from
a filesystem context created via fsopen().
Account for this case and allow the creation of detached mounts from
mounts created via fsmount(). Consequently, any such detached mount
created from an fsmount() mount will also have a zero origin sequence
number.
This allows to mount subdirectories without ever having to expose the
filesystem to a a non-anonymous mount namespace:
fd_context = sys_fsopen("tmpfs", 0);
sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
fd_tmpfs = sys_fsmount(fd_context, 0, 0);
mkdirat(fd_tmpfs, "subdir", 0755);
fd_tree = sys_open_tree(fd_tmpfs, "subdir", OPEN_TREE_CLONE);
sys_move_mount(fd_tree, "", -EBADF, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Currently, detached mounts can only be mounted onto attached mounts.
This limitation makes it impossible to assemble a new private rootfs and
move it into place. That's an extremely powerful concept for container
and service workloads that we should support.
Right now, a detached tree must be created, attached, then it can gain
additional mounts and then it can either be moved (if it doesn't reside
under a shared mount) or a detached mount created again. Lift this
restriction.
In order to allow mounting detached mounts onto other detached mounts
the same permission model used for creating detached mounts from
detached mounts can be used:
(1) Check that the caller is privileged over the owning user namespace
of it's current mount namespace.
(2) Check that the caller is located in the mount namespace of the mount
it wants to create a detached copy of.
The origin mount namespace of the anonymous mount namespace must be the
same as the caller's mount namespace. To establish this the sequence
number of the caller's mount namespace and the origin sequence number of
the anonymous mount namespace are compared.
The caller is always located in a non-anonymous mount namespace since
anonymous mount namespaces cannot be setns()ed into. The caller's mount
namespace will thus always have a valid sequence number.
The owning namespace of any mount namespace, anonymous or non-anonymous,
can never change. A mount attached to a non-anonymous mount namespace
can never change mount namespace.
If the sequence number of the non-anonymous mount namespace and the
origin sequence number of the anonymous mount namespace match, the
owning namespaces must match as well.
Hence, the capability check on the owning namespace of the caller's
mount namespace ensures that the caller has the ability to attach the
mount tree.
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-9-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Allow move_mount() to work with NULL path arguments.
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-8-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Add the ability to create detached mounts from detached mounts.
Currently, detached mounts can only be created from attached mounts.
This limitaton prevents various use-cases. For example, the ability to
mount a subdirectory without ever having to make the whole filesystem
visible first.
The current permission model for the OPEN_TREE_CLONE flag of the
open_tree() system call is:
(1) Check that the caller is privileged over the owning user namespace
of it's current mount namespace.
(2) Check that the caller is located in the mount namespace of the mount
it wants to create a detached copy of.
While it is not strictly necessary to do it this way it is consistently
applied in the new mount api. This model will also be used when allowing
the creation of detached mount from another detached mount.
The (1) requirement can simply be met by performing the same check as
for the non-detached case, i.e., verify that the caller is privileged
over its current mount namespace.
To meet the (2) requirement it must be possible to infer the origin
mount namespace that the anonymous mount namespace of the detached mount
was created from.
The origin mount namespace of an anonymous mount is the mount namespace
that the mounts that were copied into the anonymous mount namespace
originate from.
The origin mount namespace of the anonymous mount namespace must be the
same as the caller's mount namespace. To establish this the sequence
number of the caller's mount namespace and the origin sequence number of
the anonymous mount namespace are compared.
The caller is always located in a non-anonymous mount namespace since
anonymous mount namespaces cannot be setns()ed into. The caller's mount
namespace will thus always have a valid sequence number.
The owning namespace of any mount namespace, anonymous or non-anonymous,
can never change. A mount attached to a non-anonymous mount namespace
can never change mount namespace.
If the sequence number of the non-anonymous mount namespace and the
origin sequence number of the anonymous mount namespace match, the
owning namespaces must match as well.
Hence, the capability check on the owning namespace of the caller's
mount namespace ensures that the caller has the ability to copy the
mount tree.
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-6-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Add a helper that verifies whether a caller may copy a given mount tree.
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-5-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Instead of acquiring the namespace semaphore and the mount lock
everytime we close a file with FMODE_NEED_UNMOUNT set add a fastpath
that checks whether we need to at all. Most of the time the caller will
have attached the mount to the filesystem hierarchy and there's nothing
to do.
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-4-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
