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author | David Howells <dhowells@redhat.com> | 2012-02-16 17:49:54 +0000 |
---|---|---|
committer | H. Peter Anvin <hpa@zytor.com> | 2012-02-19 10:30:57 -0800 |
commit | 1fd36adcd98c14d2fd97f545293c488775cb2823 (patch) | |
tree | c13ab1934a15aebe0d81601d910ce5a3c6fa2c6f /fs/file.c | |
parent | 1dce27c5aa6770e9d195f2bb7db1db3d4dde5591 (diff) | |
download | kernel_goldelico_gta04-1fd36adcd98c14d2fd97f545293c488775cb2823.zip kernel_goldelico_gta04-1fd36adcd98c14d2fd97f545293c488775cb2823.tar.gz kernel_goldelico_gta04-1fd36adcd98c14d2fd97f545293c488775cb2823.tar.bz2 |
Replace the fd_sets in struct fdtable with an array of unsigned longs
Replace the fd_sets in struct fdtable with an array of unsigned longs and then
use the standard non-atomic bit operations rather than the FD_* macros.
This:
(1) Removes the abuses of struct fd_set:
(a) Since we don't want to allocate a full fd_set the vast majority of the
time, we actually, in effect, just allocate a just-big-enough array of
unsigned longs and cast it to an fd_set type - so why bother with the
fd_set at all?
(b) Some places outside of the core fdtable handling code (such as
SELinux) want to look inside the array of unsigned longs hidden inside
the fd_set struct for more efficient iteration over the entire set.
(2) Eliminates the use of FD_*() macros in the kernel completely.
(3) Permits the __FD_*() macros to be deleted entirely where not exposed to
userspace.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174954.23314.48147.stgit@warthog.procyon.org.uk
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/file.c')
-rw-r--r-- | fs/file.c | 46 |
1 files changed, 22 insertions, 24 deletions
@@ -40,7 +40,7 @@ int sysctl_nr_open_max = 1024 * 1024; /* raised later */ */ static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list); -static void *alloc_fdmem(unsigned int size) +static void *alloc_fdmem(size_t size) { /* * Very large allocations can stress page reclaim, so fall back to @@ -142,7 +142,7 @@ static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) static struct fdtable * alloc_fdtable(unsigned int nr) { struct fdtable *fdt; - char *data; + void *data; /* * Figure out how many fds we actually want to support in this fdtable. @@ -172,14 +172,15 @@ static struct fdtable * alloc_fdtable(unsigned int nr) data = alloc_fdmem(nr * sizeof(struct file *)); if (!data) goto out_fdt; - fdt->fd = (struct file **)data; - data = alloc_fdmem(max_t(unsigned int, + fdt->fd = data; + + data = alloc_fdmem(max_t(size_t, 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES)); if (!data) goto out_arr; - fdt->open_fds = (fd_set *)data; - data += nr / BITS_PER_BYTE; - fdt->close_on_exec = (fd_set *)data; + fdt->open_fds = data; + data += nr / BITS_PER_LONG; + fdt->close_on_exec = data; fdt->next = NULL; return fdt; @@ -275,11 +276,11 @@ static int count_open_files(struct fdtable *fdt) int i; /* Find the last open fd */ - for (i = size/(8*sizeof(long)); i > 0; ) { - if (fdt->open_fds->fds_bits[--i]) + for (i = size / BITS_PER_LONG; i > 0; ) { + if (fdt->open_fds[--i]) break; } - i = (i+1) * 8 * sizeof(long); + i = (i + 1) * BITS_PER_LONG; return i; } @@ -306,8 +307,8 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) newf->next_fd = 0; new_fdt = &newf->fdtab; new_fdt->max_fds = NR_OPEN_DEFAULT; - new_fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; - new_fdt->open_fds = (fd_set *)&newf->open_fds_init; + new_fdt->close_on_exec = newf->close_on_exec_init; + new_fdt->open_fds = newf->open_fds_init; new_fdt->fd = &newf->fd_array[0]; new_fdt->next = NULL; @@ -350,10 +351,8 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) old_fds = old_fdt->fd; new_fds = new_fdt->fd; - memcpy(new_fdt->open_fds->fds_bits, - old_fdt->open_fds->fds_bits, open_files/8); - memcpy(new_fdt->close_on_exec->fds_bits, - old_fdt->close_on_exec->fds_bits, open_files/8); + memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8); + memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8); for (i = open_files; i != 0; i--) { struct file *f = *old_fds++; @@ -379,11 +378,11 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) memset(new_fds, 0, size); if (new_fdt->max_fds > open_files) { - int left = (new_fdt->max_fds-open_files)/8; - int start = open_files / (8 * sizeof(unsigned long)); + int left = (new_fdt->max_fds - open_files) / 8; + int start = open_files / BITS_PER_LONG; - memset(&new_fdt->open_fds->fds_bits[start], 0, left); - memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); + memset(&new_fdt->open_fds[start], 0, left); + memset(&new_fdt->close_on_exec[start], 0, left); } rcu_assign_pointer(newf->fdt, new_fdt); @@ -419,8 +418,8 @@ struct files_struct init_files = { .fdtab = { .max_fds = NR_OPEN_DEFAULT, .fd = &init_files.fd_array[0], - .close_on_exec = (fd_set *)&init_files.close_on_exec_init, - .open_fds = (fd_set *)&init_files.open_fds_init, + .close_on_exec = init_files.close_on_exec_init, + .open_fds = init_files.open_fds_init, }, .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock), }; @@ -443,8 +442,7 @@ repeat: fd = files->next_fd; if (fd < fdt->max_fds) - fd = find_next_zero_bit(fdt->open_fds->fds_bits, - fdt->max_fds, fd); + fd = find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd); error = expand_files(files, fd); if (error < 0) |