kernel/linux.git/fs/afs/inode.c, branch linux-7.1.y

afs: Fix the locking used by afs_get_link()

2026-05-12T12:42:33+00:00

The afs filesystem in the kernel doesn't do locking correctly for symbolic links. There are a number of problems: (1) It doesn't do any locking around afs_read_single() to prevent races between multiple ->get_link() calls, thereby allowing the possibility of leaks. (2) It doesn't use RCU barriering when accessing the buffer pointers during RCU pathwalk. (3) It can race with another thread updating the contents of the symlink if a third party updated it on the server. Fix this by the following means: (0) Move symlink handling into its own file as this makes it more complicated. (1) Take the validate_lock around afs_read_single() to prevent races between multiple ->get_link() calls. (2) Keep a separate copy of the symlink contents with an rcu_head. This is always going to be a lot smaller than a page, so it can be kmalloc'd and save quite a bit of memory. It also needs a refcount for non-RCU pathwalk. (3) Split the symlink read and write-to-cache routines in afs from those for directories. (4) Discard the I/O buffer as soon as the write-to-cache completes as this is a full page (plus a folio_queue). (5) If there's no cache, discard the I/O buffer immediately after reading and copying if there is no cache. Fixes: eae9e78951bb ("afs: Use netfslib for symlinks, allowing them to be cached") Fixes: 6698c02d64b2 ("afs: Locally initialise the contents of a new symlink on creation") Closes: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-25-dhowells@redhat.com cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Fix potential for tearing in ->remote_i_size and ->zero_point

2026-05-12T12:42:30+00:00

Fix potential tearing in using ->remote_i_size and ->zero_point by copying i_size_read() and i_size_write() and using the same seqcount as for i_size. We need to make sure that netfslib and the filesystems that use it always hold i_lock whilst updating any of the sizes to prevent i_size_seqcount from getting corrupted. Fixes: 4058f742105e ("netfs: Keep track of the actual remote file size") Fixes: 100ccd18bb41 ("netfs: Optimise away reads above the point at which there can be no data") Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-6-dhowells@redhat.com cc: Paulo Alcantara cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

treewide: change inode->i_ino from unsigned long to u64

2026-03-06T13:31:28+00:00

On 32-bit architectures, unsigned long is only 32 bits wide, which causes 64-bit inode numbers to be silently truncated. Several filesystems (NFS, XFS, BTRFS, etc.) can generate inode numbers that exceed 32 bits, and this truncation can lead to inode number collisions and other subtle bugs on 32-bit systems. Change the type of inode->i_ino from unsigned long to u64 to ensure that inode numbers are always represented as 64-bit values regardless of architecture. Update all format specifiers treewide from %lu/%lx to %llu/%llx to match the new type, along with corresponding local variable types. This is the bulk treewide conversion. Earlier patches in this series handled trace events separately to allow trace field reordering for better struct packing on 32-bit. Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260304-iino-u64-v3-12-2257ad83d372@kernel.org Acked-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

Manual conversion to use ->i_state accessors of all places not covered by coccinelle

2025-10-20T18:22:26+00:00

Nothing to look at apart from iput_final(). Signed-off-by: Mateusz Guzik Signed-off-by: Christian Brauner

Coccinelle-based conversion to use ->i_state accessors

2025-10-20T18:22:26+00:00

All places were patched by coccinelle with the default expecting that ->i_lock is held, afterwards entries got fixed up by hand to use unlocked variants as needed. The script: @@ expression inode, flags; @@ - inode->i_state & flags + inode_state_read(inode) & flags @@ expression inode, flags; @@ - inode->i_state &= ~flags + inode_state_clear(inode, flags) @@ expression inode, flag1, flag2; @@ - inode->i_state &= ~flag1 & ~flag2 + inode_state_clear(inode, flag1 | flag2) @@ expression inode, flags; @@ - inode->i_state |= flags + inode_state_set(inode, flags) @@ expression inode, flags; @@ - inode->i_state = flags + inode_state_assign(inode, flags) @@ expression inode, flags; @@ - flags = inode->i_state + flags = inode_state_read(inode) @@ expression inode, flags; @@ - READ_ONCE(inode->i_state) & flags + inode_state_read(inode) & flags Signed-off-by: Mateusz Guzik Signed-off-by: Christian Brauner

fs: rename generic_delete_inode() and generic_drop_inode()

2025-09-15T14:09:42+00:00

generic_delete_inode() is rather misleading for what the routine is doing. inode_just_drop() should be much clearer. The new naming is inconsistent with generic_drop_inode(), so rename that one as well with inode_ as the suffix. No functional changes. Signed-off-by: Mateusz Guzik Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

afs: Locally initialise the contents of a new symlink on creation

2024-12-20T21:34:09+00:00

Since we know what the contents of a symlink will be when we create it on the server, initialise its contents locally too to avoid the need to download it. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-31-dhowells@redhat.com cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: Christian Brauner

afs: Eliminate afs_read

2024-12-20T21:34:07+00:00

Now that directory and symlink reads go through netfslib, the afs_read struct is mostly redundant with almost all data duplicated in the netfs_io_request and netfs_io_subrequest structs that are also available any time we're doing a fetch. Eliminate afs_read by moving the one field we still need there to the afs_call struct (we may be given a different amount of data than what we asked for and have to track what remains of that) and using the netfs_io_subrequest directly instead. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-24-dhowells@redhat.com cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: Christian Brauner

afs: Use netfslib for symlinks, allowing them to be cached

2024-12-20T21:34:07+00:00

Use netfslib to read symlinks, thereby allowing them to be cached by fscache and cachefiles. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-23-dhowells@redhat.com cc: Marc Dionne cc: Jeff Layton cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

afs: Use netfslib for directories

2024-12-20T21:34:07+00:00

In the AFS ecosystem, directories are just a special type of file that is downloaded and parsed locally. Download is done by the same mechanism as ordinary files and the data can be cached. There is one important semantic restriction on directories over files: the client must download the entire directory in one go because, for example, the server could fabricate the contents of the blob on the fly with each download and give a different image each time. So that we can cache the directory download, switch AFS directory support over to using the netfslib single-object API, thereby allowing directory content to be stored in the local cache. To make this work, the following changes are made: (1) A directory's contents are now stored in a folio_queue chain attached to the afs_vnode (inode) struct rather than its associated pagecache, though multipage folios are still used to hold the data. The folio queue is discarded when the directory inode is evicted. This also helps with the phasing out of ITER_XARRAY. (2) Various directory operations are made to use and unuse the cache cookie. (3) The content checking, content dumping and content iteration are now performed with a standard iov_iter iterator over the contents of the folio queue. (4) Iteration and modification must be done with the vnode's validate_lock held. In conjunction with (1), this means that the iteration can be done without the need to lock pages or take extra refs on them, unlike when accessing ->i_pages. (5) Convert to using netfs_read_single() to read data. (6) Provide a ->writepages() to call netfs_writeback_single() to save the data to the cache according to the VM's scheduling whilst holding the validate_lock read-locked as (4). (7) Change local directory image editing functions: (a) Provide a function to get a specific block by number from the folio_queue as we can no longer use the i_pages xarray to locate folios by index. This uses a cursor to remember the current position as we need to iterate through the directory contents. The block is kmapped before being returned. (b) Make the function in (a) extend the directory by an extra folio if we run out of space. (c) Raise the check of the block free space counter, for those blocks that have one, higher in the function to eliminate a call to get a block. (d) Remove the page unlocking and putting done during the editing loops. This is no longer necessary as the folio_queue holds the references and the pages are no longer in the pagecache. (e) Mark the inode dirty and pin the cache usage till writeback at the end of a successful edit. (8) Don't set the large_folios flag on the inode as we do the allocation ourselves rather than the VM doing it automatically. (9) Mark the inode as being a single object that isn't uploaded to the server. (10) Enable caching on directories. (11) Only set the upload key for writeback for regular files. Notes: (*) We keep the ->release_folio(), ->invalidate_folio() and ->migrate_folio() ops as we set the mapping pointer on the folio. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-22-dhowells@redhat.com cc: Marc Dionne cc: Jeff Layton cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner