kernel/linux.git/include/linux/dcache.h, branch v3.16.61

use ->d_seq to get coherency between ->d_inode and ->d_flags

2018-11-20T18:05:56+00:00

commit a528aca7f359f4b0b1d72ae406097e491a5ba9ea upstream. Games with ordering and barriers are way too brittle. Just bump ->d_seq before and after updating ->d_inode and ->d_flags type bits, so that verifying ->d_seq would guarantee they are coherent. Signed-off-by: Al Viro [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

VFS: Impose ordering on accesses of d_inode and d_flags

2018-11-20T18:05:55+00:00

commit 4bf46a272647d89e780126b52eda04737defd9f4 upstream. Impose ordering on accesses of d_inode and d_flags to avoid the need to do this: if (!dentry->d_inode || d_is_negative(dentry)) { when this: if (d_is_negative(dentry)) { should suffice. This check is especially problematic if a dentry can have its type field set to something other than DENTRY_MISS_TYPE when d_inode is NULL (as in unionmount). What we really need to do is stick a write barrier between setting d_inode and setting d_flags and a read barrier between reading d_flags and reading d_inode. Signed-off-by: David Howells Signed-off-by: Al Viro [bwh: Backported to 3.16: - Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE() - There's no DCACHE_FALLTHRU flag] Signed-off-by: Ben Hutchings

do d_instantiate/unlock_new_inode combinations safely

2018-10-21T07:46:03+00:00

commit 1e2e547a93a00ebc21582c06ca3c6cfea2a309ee upstream. For anything NFS-exported we do _not_ want to unlock new inode before it has grown an alias; original set of fixes got the ordering right, but missed the nasty complication in case of lockdep being enabled - unlock_new_inode() does lockdep_annotate_inode_mutex_key(inode) which can only be done before anyone gets a chance to touch ->i_mutex. Unfortunately, flipping the order and doing unlock_new_inode() before d_instantiate() opens a window when mkdir can race with open-by-fhandle on a guessed fhandle, leading to multiple aliases for a directory inode and all the breakage that follows from that. Correct solution: a new primitive (d_instantiate_new()) combining these two in the right order - lockdep annotate, then d_instantiate(), then the rest of unlock_new_inode(). All combinations of d_instantiate() with unlock_new_inode() should be converted to that. Tested-by: Mike Marshall Reviewed-by: Andreas Dilger Signed-off-by: Al Viro [bwh: Backported to 3.16: - Drop changes in orangefs - Apply similar change to ext3 - Adjust context] Signed-off-by: Ben Hutchings

dentry name snapshots

2017-08-26T01:14:48+00:00

commit 49d31c2f389acfe83417083e1208422b4091cd9e upstream. take_dentry_name_snapshot() takes a safe snapshot of dentry name; if the name is a short one, it gets copied into caller-supplied structure, otherwise an extra reference to external name is grabbed (those are never modified). In either case the pointer to stable string is stored into the same structure. dentry must be held by the caller of take_dentry_name_snapshot(), but may be freely dropped afterwards - the snapshot will stay until destroyed by release_dentry_name_snapshot(). Intended use: struct name_snapshot s; take_dentry_name_snapshot(&s, dentry); ... access s.name ... release_dentry_name_snapshot(&s); Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name to pass down with event. Signed-off-by: Al Viro [carnil: backport 4.9: adjust context] [bwh: Backported to 3.16: - External names are not ref-counted, so copy them - Adjust context] Signed-off-by: Ben Hutchings

VFS: Introduce inode-getting helpers for layered/unioned fs environments

2015-07-15T09:01:05+00:00

commit 155e35d4daa804582f75acaa2c74ec797a89c615 upstream. Introduce some function for getting the inode (and also the dentry) in an environment where layered/unioned filesystems are in operation. The problem is that we have places where we need *both* the union dentry and the lower source or workspace inode or dentry available, but we can only have a handle on one of them. Therefore we need to derive the handle to the other from that. The idea is to introduce an extra field in struct dentry that allows the union dentry to refer to and pin the lower dentry. Signed-off-by: David Howells Signed-off-by: Al Viro [ luis: 3.16 prereq for: fbabfd0f4ee2 "fs: Add helper functions for permanently empty directories." ] Signed-off-by: Luis Henriques

move d_rcu from overlapping d_child to overlapping d_alias

2015-01-15T10:44:58+00:00

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream. Signed-off-by: Al Viro [bwh: Backported to 3.16: - Apply name changes in all the different places we use d_alias and d_child - Adjust context] Signed-off-by: Ben Hutchings Cc: Moritz Muehlenhoff Signed-off-by: Luis Henriques

dentry_kill(): don't try to remove from shrink list

2014-05-01T14:30:00+00:00

If the victim in on the shrink list, don't remove it from there. If shrink_dentry_list() manages to remove it from the list before we are done - fine, we'll just free it as usual. If not - mark it with new flag (DCACHE_MAY_FREE) and leave it there. Eventually, shrink_dentry_list() will get to it, remove the sucker from shrink list and call dentry_kill(dentry, 0). Which is where we'll deal with freeing. Since now dentry_kill(dentry, 0) may happen after or during dentry_kill(dentry, 1), we need to recognize that (by seeing DCACHE_DENTRY_KILLED already set), unlock everything and either free the sucker (in case DCACHE_MAY_FREE has been set) or leave it for ongoing dentry_kill(dentry, 1) to deal with. Signed-off-by: Al Viro

vfs: add cross-rename

2014-04-01T15:08:43+00:00

If flags contain RENAME_EXCHANGE then exchange source and destination files. There's no restriction on the type of the files; e.g. a directory can be exchanged with a symlink. Signed-off-by: Miklos Szeredi Reviewed-by: Jan Kara Reviewed-by: J. Bruce Fields

vfs: add d_is_dir()

2014-04-01T15:08:41+00:00

Add d_is_dir(dentry) helper which is analogous to S_ISDIR(). To avoid confusion, rename d_is_directory() to d_can_lookup(). Signed-off-by: Miklos Szeredi Reviewed-by: J. Bruce Fields

dcache: allow word-at-a-time name hashing with big-endian CPUs

2013-12-12T18:39:01+00:00

When explicitly hashing the end of a string with the word-at-a-time interface, we have to be careful which end of the word we pick up. On big-endian CPUs, the upper-bits will contain the data we're after, so ensure we generate our masks accordingly (and avoid hashing whatever random junk may have been sitting after the string). This patch adds a new dcache helper, bytemask_from_count, which creates a mask appropriate for the CPU endianness. Cc: Al Viro Signed-off-by: Will Deacon Signed-off-by: Linus Torvalds